[stelles]

If people ask, it's none of their business. Just say something vague like, "I was sick" or "Family emergency" or "Something came up." If they keep asking, it's none of their business, and you can tell them that. And if someone asks why you didn't answer your phone you can say you lost it or didn't feel like answering.
As for health class, that does sound like an issue. But again, if someone asks if you attempted suicide, you can always go with "none of your business" or even just tell them straight out that that's not what happened. I feel kinda bad telling you to lie, but it's your life and people shouldn't pry into it.
You can ask a teacher or guidance counselor why you were taken off the attendance list. I'm not sure why you were but I think someone at school could probably tell you. It might just be because they knew you would be out for a while.
Good luck with everything