Why do i smell bad? please help!?

This has been going on since i was in middle school and now I am a senior in high school and I still don't know what is wrong with me. I was fairly popular in both middle school and high school but people seemed to comment on my "scent". Even close friends of mine will make obvious comments like, "it smells like a diaper!" or "who pooped their pants?" I have tried asking them if I am the one that smells and they just say no, but whenever I bring it up they seem to avoid the question and quickly change the subject. I have developed intense social anxiety due to this problem and I have tried everything to stop it including showering twice a day, wearing cologne, thoroughly washing my clothes but nothing works! I have two dogs who do smell pretty bad at times so I was thinking it could be the smell of dog or my overall house smell. I never smell anything when I sniff my clothes and armpits a good sniff either. Finally, in this past year I've been having issues with wiping after going Number 2. I wipe thoroughly and make sure there isn't anything there after I finish, but 5 minutes later it feels itchy down there and when I go back to wipe there is poo on the toilet paper. I'm not sure if this is some kind of bowel dysfunction or what. I eat a fairly healthy diet, and no I have never had anal sex and I never will...could it be hemorrhoids? Someone please help me with this issue, it's caused me to avoid friends and other social gatherings, not to mention that girls hardly ever talk to me anymore. Any insight or advice on this matter is much appreciated. Thanks again