You're his mother and if you think weed started this crazy train then you may be right. For most people weed is ok but for a select few it can be a terrible terrible thing. Also weed is unregulated and could have been laced with something that sent him off the rails.

Long ago when I was a teeny bopper I smoked some that had been mixed with something and I didn't know where I was or who I was. I didn't even recognize my own mother. It was terrifying. She found me leaning against a wall on Bourbon street in New Orleans, she just happened to be walking by. I thought I was home in bed and couldn't figure why there was so many people in my room. Was I psychotic at that time? Yes. That was the only time I've ever been psychotic. That was 45 years ago.

My heart goes out to you.