The time I quit smoking weed, was the time I had a horrific experience with it. I hallucinated to the point of utter insanity. It was not laced and I wasn't on anything else. I think my anxiety while smoking and everything that was going on at the time made it so horrible. It was like a panic attack and felt (if I were to judge how a schizophrenic moment would feel) very schizophrenic. I had these crazy ideas that questioned my life to the scariest point.
From there on, my dreams were on a roller-coaster. From the anxiety and from my weed-induced breakdown, my mind had opened the lock to thoughts that belonged another dimension. I had no structure in the concept of life, and it was reflected in my dreams. Hopefully this is making sense to you.
I also have had doctors suggest I have PTSD - and I used to regularly self-medicate (instead of actually asking for some medication to help). By this, it intensified the situation because I was not working on trying to overcome some of PTSD's aspects.
I'm glad to hear you haven't smoked in a long time. It's been awhile for me too. Everything feels so much more real now.