Not a bad idea to also get his testosterone checked as well, so if I were you I'd suggest he see and Endocrinologist to get everything checked out. I also feel it's the best place to start before assuming it's anxiety. Best wishes!
Caffeine could be one reason. Has he been to a doctor to have his thyroid checked? Or it could even be an adrenal gland issue too. Those sources are a little on the extreme end but if eliminating caffeine doesn't help then maybe he should see a doctor.
The coffee can have a signaficant factor as well as energy drinks. I would like to drink energy drinks but it would make my heart beat so fast that i thought i was dieing. Try to avoid caffinated drinks.
This seems to me to be a start of a panic attack coming along. I would get that alot in my college classes. I would feel all jittery, and all of a sudden this nasty feeling hot sensation in my body, then heavy breathing, etc.