A friend of mine is writing a fanfic and i'm just helping her ask here. The plot requires the main character (a guy, 20 years old) to develop some sort of disease (might be cancer?) to make his ex girlfriend feel sorry for him and *feel in lame, corny storyline that goes from here*. The disease needs to be detectable (whether by symptoms or scans/tests), lasts more than 3 months, and the person who has the disease has to be abled to be cured and fully recover from it (without losing any limbs or having much change in physical appearance).
Question: What should the disease be? And for those who answer cancer, what kind of cancer (like what body part)?