Don't worry about it and go back. You didn't really even fuck up - it's not like you went "let me throw up here and see what happens". I've vomited in very public places before. It can happen to anyone.

Oof, that's just terrible. But then again, how likely is something like this to happen, given all the factors that would need to coincide for it? Like OP said, it was far more likely that he gets himself killed by believing he can fly or walk through traffic.

Could be... Maybe I don't know enough about what acid does to you (never tried it or anything silimar), but as far as I'm aware it's not a drug that turns you violent or destructive in any real way. But yeah I guess it was enough to make the school staff/meds to get worried about others' safety.

As for public indecency, I know that the US has pretty harsh laws regarding public nudity, so perhaps it was their way of punishing him for that without actually evoking the specific charges given that OP was high af during that time.

This might be an unpopular opinion, but actually I think it's kind of fucked to even be expelled for 6 months over something like this... I mean, it's not like OP killed or injured anyone, deliberately exposed himself to a minor, etc. A month or two at most for disturbing public order would have done. Regarding fireworks, expulsion is more or less justified actually, because they can start a fire with potentially far more severe consequences.