there is nothing you can do to help him. he's obviously having some issues in his head, which is why he doesn't want to smoke anymore, but it's not the marijuana, i'll tell you that much. do you notice any personality issues with your friend? does he act strange sometimes or different? he's being paranoid, which is probably making him anxious.

this is all the advice i can give since i myself do not know the kid and some shit i have to say might not absorbed due to neglegence or denial. it's all in his head brother.