(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.