For me, it was fear of sucking my thumb at the approximate age of 11. I was afraid I would do this and embarrass myself, so I was very nervous about staying over at a friend's house. I solved this by telling my friend in the morning that I dreamed that I was sucking my thumb! I was a bundle of anxiety all of my life and I think it had much to do with the horrid way I was raised. Thumb sucking was a sign of my awful insecurity. I do NOT mean to imply that this is your problem at all, Mercury Fumes.

I agree that you should seek counseling and find out what causes you have this problem, where it originated from in your earlier life. Best of luck!
Big Hug