One of my best friends, a girlfriend from high school (we're 60 now) had a similar experience to yours when we were in college. I think I remember she was in grad school, so about 1974. She said she was smoking marijuana at a party and almost jumped off a balcony. It scared her so bad she hasn't smoked since.

Anxiety feeds on itself. I would think too, that the anxiety and depersonalization would too, especially perhaps at your age. I started therapy in college when I was 20 because of anxiety over changes in my life (growing up, going out in the world, being an adult and having to live my own life/be responsible for myself) and it got a lot worse in my mid-20's before it got better (in my 30's).