I have migraines, which developed in adulthood. I feel terrible for any child who must cope with them. They can be absolutely debilitating, and frankly he should be allowed to come home from school. I'm no expert, but he probably needs a medical plan (504?) to handle that because it really can be a very serious problem. I would freak out on people too if I were a young child trying to cope with that in a school environment.

Other than that, the bear hugs issues makes me think of sensory processing disorder. Are you familiar with that?