For people saying that you could drug test him, you really can't do it with urine / blood tests because there will still be residual weed in his system for up to 4-6 weeks (i.e. he could still test positive for weed that he was using pre-psychotic episode).

Sounds scary. I hope he's alright. Suspecting that people are playing "mind games" with him sounds a LOT like what happened to me during my manic episode with psychotic features last year.