I will say that kids with
adhd can have several anxiety about school (due to their
adhd) and this can manifest itself in many ways.
His eating habits are a bit unusual. However, one of the prime symptoms of adhd is acting without thinking (which the correct dose of medication can really help). And, of course, anxiety can cause all kinds of unusual eating habits.
So I think that you need to spend your time researching adhd (I can help with this) and working with your school.