It sounds like he wants someone who can pick up and go at will. No restrictions. I think you would be in this situation even if you didn't get sick. From your postings he sounds like a typical guy who likes to go bar hopping, parties, travel at spur of the moment, etc.
It sound like you weren't like that before you got sick and now that you are sick you physically can't go along and "give-in" to him everytime. I think getting sick may have put into light the big differences in your relationship with him. You are both young and both finding out who you are.
You are right he is using your sickness as an excuse to end it. Before you got sick, I am sure you argued about these types of things until you gave in and went or had a fight. Now that you can't give in because you physically can't do it, its showing him how different you 2 really are. I would let him go. If he is right for you he will come back when he grows up.
You are not asking a lot. You are giving him his freedom to do things when you can't. No questions asked. You have to take care of yourself with this disease. The STRESS you are having with this now is probably making your bathroom pretty interesting. LOL!
He wants OUT of the relationship. He is all but telling you to break up with him. It will be hard and painful. But I believe its something you have to do.