OK, so remember I was talking about the epsom salt bath? It really did the trick. Clark slept through the night! Yay!
The only other problem? It seems that the two days of constant stimming reminded him of all of his previous bad behavior.
So he remembered about yelling, and running around on the school bus, and chasing our cats...oi.
The tentative plan right now is to give him 1/8 tsp at breakfast tomorrow and a salt bath at night, rinse, repeat.
We'll see how it goes. And we'll also see how taking away toys and privileges works for the behavior.