Although you should check with a dr., I would have to say that the main thing is that distinguishes what you are experiencing from psychosis, is that you stated you rationally know that you are not under threat. In psychotic paranoia, the paranoia is the reality... one cannot normally distinguish what is rational from what is felt.

I have often experienced a form of anxiety that would be classified as paranoid-- fearing that someone put something in my drink when I wasn't looking, fearing that the car behind me is following me-- all of this equates to a huge fear of something catastrophic happening-- being poisoned, killed, etc.

Your paranoia, like mine, is of known origin. You know exactly where this came from. You seem to be completely in touch with reality. You obviously have excellent insight, as you were able to analyze the origins of your anxiety right there in your post.

To me this sounds as though your anxiety is manifesting itself through these paranoid thoughts.