Things I'm thinking
about could be things like having his seat changed in class so he's next to someone he has conflict with, learning new skills at school that he's not confident
about and is struggling with, some new kind of food he's ingesting at school that has something that's irritating his system (
artificial dyes or
sweeteners would be my first guesses), something other kids are talking
about that are scaring him (movies or tv shows or
stories).