Hi Narim and welcome to the site
Your posting is very interesting and I read it a couple of times to be sure I got it all. In my own opinion I would not worry that you have a mental illness.
It's hard to say if the pot did this. You said the near death experience came after smoking pot but I'm not sure if you were smoking when you started having all the deja vu's.
My spirituality leads me to believe in psychic energy and thoughts; however, I'm not saying you are psychic. I don't believe psychics can see what their own life is going to do. However, one can be so connected with themselves and the universe that they can have psychic experiences.
Again, my own belief is that when we were on other side we planned the life that we are currently in. We planned the good, the bad, and the ugly because it was what we felt we needed to learn. Having said that, deja vu makes sense doesn't it? I have deja vu quite often and instead of being scared I get a bit excited because it makes me stop and think about the situation I'm in and do I need to learn from it.
You sound like a very intelligent and insightful person. I would not let this get to you. I would recommend however that you nix the pot - it really can lead you down a path of disaster. Alot of people say it can't, but I am in recovery and have seen alot of people who are alcoholics (as am I) who turned to pot to try to get off booze and it just didn't work.
Take care and good to hear from you.
Tranquility