Somebody who understands psychology, answer this -?

I'm a healthy, 18-year-old who is homeless right now, so I am sleeping on the streets.. Instead of laying down to sleep, I stand up so I don't get robbed beaten up. Later in the night I start uncontrollably roaming the town, hallucinating as I go along. Everything looks like i'ts moving and might attack me and then i'll go to the side of the street and completely stare down passer-bys. I don't like this and I want it to stop. It feels like i'm on some hard-core drug and I'm halfway dreaming. So the question is- what is causing this and how do I get it to stop.?