What is a diseases/disorders that meet this criteria? (for a novel in progress)?!

What is a diseases/disorders that meet this criteria? (for a novel in progress)?

I'm writing a story, and to fulfil the plot, three characters need to enter the hospital. I have decided how two of the characteres will enter , but I'm unsure how the last should enter.

It is for a boy (Yan) aged somewhere between 19-21. Throughout the story he will appear to be fine (until he can't hide it anymore), but he know's he isn't well. He will visit the hospital frequently, but will live at home. His mother also died of an unmentioned condition (so, the boy's condition could but doesn't have to be genetic).

The boy will be unter intense stress as a result of raising his younger brother, dealing with his father's past actions against Yan's mother (alcoholism, adultry, and divorce), working throughout the day, continuing college courses through correspondance at night, and finding a way to keep his mother's house (and other financial issues). So, the disease can be a result of or intensified by his stress' affect on his immune system.

2 weeks ago
This disease or the effects thereof will ultimately result in this characters death in the course of 1-2 years, but its effects should still be subtle because he must still live at home.

How about Crohn's disease? It is an auto immune, gets worse with stress and people can die from it. You can contract Crohn's at any age.