I do not watch scary movies at all because they make me feel bad. Some people think it's okay to to watch horror movies and they have no issue with them. I once was with a group of people and they were watching a movie I couldn't leave. I still felt altered the next day.

Being a teenager isn't a walk in the park with all that hormonal stuff going on it's own. Try to steer clear of it for a little while to give yourself a break to see if you feel any better. Is there a counsellor at the school you could talk to?