If so, then there's some good news, you aren't alone and someone's got a solution for you.
I too am one of those individuals that suffers from slight paranoia when smoking a bowl (The cats are giving me funny looks...) and by talking to other grass users I constantly encountered others who experienced the same thing. I ran into Bryan Basamanowicz today on the streets of Vancouver while he was promoting his book and the subject caught my attention. Here's a video blurb about the book and the support group he runs those who has this issue with marijuana.