Friend won't tell me why he's in hospital

My friend/housemate went into hospital recently and didn't tell me why before he went, and still hasn't even though I've asked directly in a text, and in person before he went. I have been worrying myself into a terrible state of mind for about 3 days now. This was going to be a very stressful time anyway, but it's that much worse because of not knowing that. There wasn't anything obvious before he left. He also only told me he was going to stay in the hospital (for 1 night initially) just as he was about to walk out the door to go there, then was like "I've got to go" like it was my fault he was dropping that bombshell when there wasn't time to have the necessary length of conversation for that kind of news. Now I feel angry and hurt at the way I've been treated and shut out and it has brought up issues about does he care about/actually want much to do with me? I think it's a time like this that people show who they really want. I'm desperate to know if he's ok, and he sends me a couple of short, cold, uninformative texts. I also sent him one saying I miss you and he didn't say it back. Now when he comes back I will feel like being bringing this up, but I won't actually because that is not an appropriate time. I'm not sure if he is either a. not bothered about being friends with me b. not wanting to show anything inner/emotional (he does have problems with communicating) c. does something where he tells people closest to him the least or if I have a tendency to think other people don't care about me much. Since I live with him as well as being friends and caring about him that much, I don't want to be shut out or one of the last people to know, while strangers get to know more and first. When I get to know, it's probably going to be too little, too late.

Thanks for reminding me why I don't usually post in online forums. If I could downvote that answer I would. Yes, why someone is in hospital is always highly personal, but people spend hours just waiting in hospital waiting rooms for that information, and they get it. I respect people's privacy enough, thank you very much, but he could die in there before I knew what was even wrong for all I know. The only time people don't get to know what happened to their loved ones is when nobody knows that. It's making me even more distraught that they're extending his stay. The mental and physical state I'm getting myself into right now, I could join him in the hospital. I'm prone to get depressed when something goes wrong, and was distraught enough to want to talk to somebody about this and get some emotional support, but this is obviously the wrong place to do it. All I've received is a post hurling a false accusation, and I would advise other people with depression not to post here, you don't need to be made to feel worse when you feel that bad already.