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.
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.