[throwaway9839]

I had a similar experience (depersonalization) also caused by marijuana. Mine lasted for several months until I was back to normal-ish. It was very scary and disorienting.

For anyone experiencing this, I have three pieces of advice: (1) Don't worry too much. Things will get back to normal, and worrying is part of the cause. (2) Try meditating. When I started to meditate while depersonalized, the effect was incredible: it changed from a negative experience to a very positive one. I'm now actually glad for the experience overall, despite the initial scariness. (3) Your worldview is changing. Try not to fight it too much.