I'm so sorry to hear this Artemis. What a difficult situation. I feel for your boy and you as well. I don't know what his doctors say, but yeah, it sounds like rehabs aren't the answer.
I'm sure you've already seen neurologists, right?

Cannibis is legal here in Maine, but I don't know if it would help. Wish I could offer more. Narcotics Anonymous saved my life. It focuses on abstinence from all drugs.

I will say a prayer for you and your son, and hopefully relief will come soon.

Best,

Vicki