I happen to be the exact same way. I believe everything is wrong with me, being cancer, aids, a loose tooth, poisoning, anything. It started a long time ago, I thought I had consumed some sort of acid and my grandfather told me butter would neutralize it, needless to say, I ate a few sticks of butter. I'm not exactly sure why I started being paranoid about things, but I'd have sex with some girls, with protection, and then worry a few weeks about having aids. Same with cancer, I constantly check my phlegm for any traces of blood (I make my throat bleed from coughing up plelgm so much).