Solange Knowles at the Milly By Michelle Smith Fashion Show during Spring 2016 New York Fashion Week at Art Beam
Ben Gabbe/Getty Images North America/Getty Images
Solange Knowles at the Milly By Michelle Smith Fashion Show during Spring 2016 New York Fashion Week at Art Beam
Now playing
00:36
Solange reveals illness, cancels show
HOLLYWOOD, CA - JUNE 22:  Carrie Underwood attends the 2018 Radio Disney Music Awards at Loews Hollywood Hotel on June 22, 2018 in Hollywood, California.  (Photo by Rich Fury/Getty Images)
Rich Fury/Getty Images
HOLLYWOOD, CA - JUNE 22: Carrie Underwood attends the 2018 Radio Disney Music Awards at Loews Hollywood Hotel on June 22, 2018 in Hollywood, California. (Photo by Rich Fury/Getty Images)
Now playing
01:43
Carrie Underwood reveals pregnancy struggles
INGLEWOOD, CA - DECEMBER 01:  (EDITORIAL USE ONLY. NO COMMERCIAL USE) Demi Lovato in the press room during 102.7 KIIS FM's Jingle Ball 2017 presented by Capital One at The Forum on December 1, 2017 in Inglewood, California.  (Photo by Alberto E. Rodriguez/Getty Images for iHeartMedia)
Alberto E. Rodriguez/Getty Images
INGLEWOOD, CA - DECEMBER 01: (EDITORIAL USE ONLY. NO COMMERCIAL USE) Demi Lovato in the press room during 102.7 KIIS FM's Jingle Ball 2017 presented by Capital One at The Forum on December 1, 2017 in Inglewood, California. (Photo by Alberto E. Rodriguez/Getty Images for iHeartMedia)
Now playing
00:45
Demi Lovato 911 call: 'No sirens, please'
Gretchen Wilson arrives at the 50th annual CMA Awards at the Bridgestone Arena on Wednesday, Nov. 2, 2016, in Nashville, Tenn. (Photo by Evan Agostini/Invision/AP)
Evan Agostini/Invision/AP
Gretchen Wilson arrives at the 50th annual CMA Awards at the Bridgestone Arena on Wednesday, Nov. 2, 2016, in Nashville, Tenn. (Photo by Evan Agostini/Invision/AP)
Now playing
00:50
Country singer arrested after airport incident
French actor Gerard Depardieu waves as he arrives at the Town Hall  in Brussels for a ceremony as part of the 'Brussels International Film Festival' (Briff) on June 25, 2018. (Photo by THIERRY ROGE / BELGA / AFP) / Belgium OUT
THIERRY ROGE/AFP/AFP/Getty Images
French actor Gerard Depardieu waves as he arrives at the Town Hall in Brussels for a ceremony as part of the 'Brussels International Film Festival' (Briff) on June 25, 2018. (Photo by THIERRY ROGE / BELGA / AFP) / Belgium OUT
Now playing
01:36
Actor Gérard Depardieu accused of rape
HOLLYWOOD, CA - MAY 18:  Actor Johnny Depp attends the premiere of Disney's 'Pirates Of The Caribbean: Dead Men Tell No Tales' at Dolby Theatre on May 18, 2017 in Hollywood, California.  (Photo by Rich Fury/Getty Images)
Rich Fury/Getty Images North America/Getty Images
HOLLYWOOD, CA - MAY 18: Actor Johnny Depp attends the premiere of Disney's 'Pirates Of The Caribbean: Dead Men Tell No Tales' at Dolby Theatre on May 18, 2017 in Hollywood, California. (Photo by Rich Fury/Getty Images)
Now playing
01:16
Johnny Depp's candid Rolling Stone interview
vince vaughn arrest dui orig sc_00000000.jpg
Manhattan Beach Police
vince vaughn arrest dui orig sc_00000000.jpg
Now playing
01:15
Actor Vince Vaughn arrested for DUI
Jada Pinkett Smith suicide orig mg rf_00003425.jpg
Megyn Kelly TODAY
Jada Pinkett Smith suicide orig mg rf_00003425.jpg
Now playing
01:15
Jada Pinkett Smith on having suicidal thoughts
AFP/Getty Images
Now playing
00:53
Country superstar apologizes for Trump comment
HOUSTON, TX - FEBRUARY 04:  Rapper Meek Mill arrives for the Fanatics Super Bowl Party at Ballroom at Bayou Place on February 4, 2017 in Houston, Texas.  (Photo by Robin Marchant/Getty Images for Fanatics)
Robin Marchant/Getty Images
HOUSTON, TX - FEBRUARY 04: Rapper Meek Mill arrives for the Fanatics Super Bowl Party at Ballroom at Bayou Place on February 4, 2017 in Houston, Texas. (Photo by Robin Marchant/Getty Images for Fanatics)
Now playing
02:11
Meek Mill's legal saga
Now playing
00:54
Will Ferrell involved in car accident
Roc Nation
Now playing
01:12
Meek Mill released from prison
NEW YORK, NY - NOVEMBER 14:  Wendy Williams attends the 50th anniversary celebration of Wilhelmina with co-host Patti Hansen on November 14, 2017 in New York City.  (Photo by Ilya S. Savenok/Getty Images for Wilhelmina Models)
Ilya S. Savenok/Getty Images North America/Getty Images for Wilhelmina Mode
NEW YORK, NY - NOVEMBER 14: Wendy Williams attends the 50th anniversary celebration of Wilhelmina with co-host Patti Hansen on November 14, 2017 in New York City. (Photo by Ilya S. Savenok/Getty Images for Wilhelmina Models)
Now playing
00:47
Wendy Williams on hiatus after diagnosis
Julia Louis-Dreyfus/Twitter
Now playing
01:08
Julia Louis-Dreyfus shares post-op photo
Singer Lana Del Rey performs at Terminal 5 on October 23, 2017 in New York City.  (Photo by Mike Coppola/Getty Images)
Mike Coppola/Getty Images
Singer Lana Del Rey performs at Terminal 5 on October 23, 2017 in New York City. (Photo by Mike Coppola/Getty Images)
Now playing
00:43
Man arrested outside Lana Del Rey concert
Lady Gaga arrives for the 60th Grammy Awards on January 28, 2018, in New York.  / AFP PHOTO / ANGELA WEISS        (Photo credit should read ANGELA WEISS/AFP/Getty Images)
ANGELA WEISS/AFP/AFP/Getty Images
Lady Gaga arrives for the 60th Grammy Awards on January 28, 2018, in New York. / AFP PHOTO / ANGELA WEISS (Photo credit should read ANGELA WEISS/AFP/Getty Images)
Now playing
00:54
Lady Gaga cancels final tour dates
(CNN) —  

Solange Knowles has canceled her New Year’s Eve gig at the AfroPunk festival in South Africa, blaming health issues.

The singer/DJ, who performs under her first name, revealed Wednesday in an Instagram post that she has been dealing with an illness.

“The past five months I have been quietly treating, and working through an Autonomic Disorder,” she wrote. “It [sic] been a journey that hasn’t been easy on me.”

According to the Mayo Clinic, autonomic nerve disorders affect the autonomic nervous system, which controls a person’s involuntary functions.

“Symptoms are wide-ranging and can include problems with the regulation of heart rate, blood pressure, body temperature, perspiration, and bowel and bladder functions,” says the Mayo Clinic’s website. Other symptoms include fatigue, lightheadedness, feeling faint or passing out, weakness and cognitive impairment.

Knowles, 31, younger sister of superstar Beyoncé, had been set to headline the festival in Johannesburg, which will run from December 30 to January 1.

The singer wrote on Instagram that she had struggled with finding the words to describe her condition.

“However it’s so important to me for the people in South Africa, a place that has tremendous meaning to me and that has given me SO SO MUCH, to know why I won’t be performing at Afro Punk this NYE,” she wrote.

“Sometimes I feel cool, and other times not so cool at all,” she said of living with the disorder. “It’s a complicated diagnoses [sic], and I’m still learning so much myself, but right now, my doctors are not clearing me for such an extended lengthy flight, and doing a rigorous show right after.”

Solange vowed to return for a concert in Johannesburg later in 2018.

In a Facebook post Thursday, the AfroPunk festival said it only learned “within the last day” that Solange was canceling her appearance.

“We value her as an artist and above all as a human being and understand that her health is paramount,” the festival said in a statement. “Though we have worked with Solange on multiple festivals this year, we were not among the few who were aware that she has been privately dealing with this diagnosis. We believe and trust her commitment to grace the 2018 AFROPUNK Joburg stage.”

In her post Solange thanked AfroPunk and organizers of other festivals, as well as friends and family who knew of her diagnosis and kept it quiet.

The singer vowed to do better with her self-care in 2018 and had words of gratitude for her fans.

“Performing this record and experiencing the energy exchange with you guys has been astounding, and I’m so excited about continuing to do the work I feel so absolutely humbled and appreciative to be doing next year,” she wrote. “It gives me life.”