Is it possible to get headaches from doing nothing all day? i'm always inside my apartment i never go out or do anything so could that be one reason?

Nothing isn't good: The absence of so much is clearly not the way a young adult is intended to live. Prison reform has even demanded more for inmates. But this wouldn't directly cause a headache. It might indirectly and other problems too. You don't say 'why?' but unless there's an insurmountable obstacle - please make changes. Try good therapy to help - change is their thing!