This character suffers from an illness or disease.
A disease or illness is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs.
It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune diseases.
Illnesses and diseases usually affect people not only physically, but also emotionally, as contracting and living with many diseases can alter one's perspective on life, and their personality.