J.S.
I have two boys. The oldest would do things like this when he was upset about something else. Usually I could drag it with a day of following him and asking a lot of questions. I would really focus on his day at school there maybe something going on there. Teachers do miss things sometimes.
My youngest it is usually a schedule change. A day off, new teacher, sleep times or even the cold, it takes almost two weeks sometimes for him to 'adjust' with a little less drama day by day.