It sounds like an Obsessive/compulsive disorder {OCD}-
We have a forum that may be of help-
http://neurotalk.psychcentral.com/forum50.html

If you aren't wanting to seek professional help with it yet, there might be other methods you can try.
self help or online hypnosis - books , CDs etc
distraction techniques
EFT - free beginner info package -
http://www.emofree.com/downloadeftmanual.asp