Sexual and hypochondriatic paranoia

For the last 5 years now i have been paranoid. I generally ahve quite a paranoid personality, but it only became seious when i started to believe for a whole year that i had testicular cancer. I think it was because there were so many adverts on T.V. n evrywhere about it, and even though sometimes i knew i was being ridiculous i even went to the doctors about it, though i never followed it up. I finally got over this certain paranoia by telling myself that it was stupid and i had given it a year and nothing had developed so i couldn't have it.
Now i have got over that paranoia ORBNE2i am starting to wish i still had it because the one i have now is so much worse. I started to think i might be gay, even though i have a girlfreind in a very long term relationship who i love so much it hurts. I don't get turned on by boys, and i have a great sex life with my girlfriend, so i don;t see why i think like this? Can you explain and how can i get rid of it like the cancer.