Two things came to mind:

The idea that people know something you don't is an implication of the possibility of delusions of persecution. Not necessarily that they are "out to get you" but more that they are "keeping something from you" that you feel you need to know.

The next thing I thought of was disassociation, the feeling that you aren't really there, or don't really belong. I recommend a bit of research and a consultation with a counselor.