(CNN) -- A 13-year-old Minnesota boy who has cancer has resumed chemotherapy treatments and is not responding well, a family spokesman said Friday.
Doctors say Daniel Hauser's lymphoma responded well to a first round of chemotherapy in February.
Danny Hauser started a second round of chemotherapy treatment this week, Jim Navarro said in a statement on the family's Web site, dannyhauser.com.
"The doctor changed the number of chemotherapy drugs in the protocol submitted to the court. Danny is not tolerating the drugs well and has been vomiting all day. He is understandably angry and depressed about being forced to go through the ravages of chemotherapy again."
Daniel underwent his first round of chemotherapy in February, a month after he was diagnosed with Hodgkin's lymphoma. But his parents were concerned about the treatment's side effects, which typically include nausea, and decided to end the chemotherapy regimen and pursue holistic treatments instead.
When Daniel's oncologist learned of the decision to reject standard treatment, which doctors say is associated with a cure rate of as high as 90 percent, he asked a court to intervene to ensure the teen got chemotherapy.
Doctors say that, without it, the disease would likely prove fatal.
But last week, before the court could act, Colleen Hauser packed up her son and flew with him to Southern California, from where they were planning to continue to Mexico to seek alternative alternative medical treatment. She said he would have run on his own had she not helped him flee.
She changed her mind before crossing the border and returned this week with Daniel to Minnesota, where the family agreed to comply with whatever treatment the court ordered.
A medical examination revealed that the boy's tumor had grown since he was diagnosed and the boy's doctor recommended he resume chemotherapy.
After examining the boy on Monday, Dr. Michael Richards estimated the tumor's size at 5.3 inches by 5.1 inches by 6.3 inches, and said it was "protruding outside the chest wall."
He said initiation this week of standard chemotherapy treatment was "imperative."
Richards recommended at least another five cycles of chemotherapy followed by radiation, and added that the "goal will be to include alternative therapies in which the family is interested, as long as there is not data to suggest that a particular danger exists with any alternative medicine."
District Court Judge John Rodenberg originally took custody of the boy away from his parents, but returned him to his family on the condition that they comply with the recommendations of the cancer specialist.
Hodgkin's lymphoma is a cancer that affects the lymphatic system, which is part of the immune system. As the disease progresses, it compromises a body's ability to fight infection.
CNN's Aaron Cooper contributed to this story.