I had the same problem after a bad stint with mushrooms. I literally thought I was in hell. It was sheer terror (I was 16 when this happened). For the next year I had all the symptoms you did. And when I smoked it would put me in a flashback to the same place. So I stopped all drugs for about three years and slowly I went back to "normal". When I now analyse what happened, it was ptsd. Mental terror is a shitty thing, but stay strong, get involved in life and you'll get better. I'm now at a point where I can smoke again (I don't do it a bunch but I do like 0-3 times a week) I tripped mushrooms again, and I'm fine. You'll get trough it on your own, it was only a tough lesson that abusing drugs isn't good. Use in moderation.