Mark - thanks for the insight re scans.

The way I described the "shiver" is based on what I observe the action as - what he actually feels isn't a shivering sensation per se, but he hasn't been able to articulate why he does it or what he feels when it happens. He just says it feels good to do it when he does it.

Agreed re treatment. It's clear that the jump into the classroom after the weekend makes him feel lousy, and that the rest at home keeps him on an even keel.

I feel pretty lucky that what we're experiencing is very surmountable for now and relative to what others endure, pretty benign.