Why do I smell like poop?

I have a issue here. I always used to smell great, and I have carried the same good hygiene for a long time. It wasn't until a few months ago, where I really began to smell like human poop. I would take long showers before school, and even at night; and immediately afterwards, I would usually begin to smell like poop. I have tried using different soaps, etc. and it hasn't seemed to work. I'm a caucasian male; freshman in high school, and it' kind of embarrassing when people say "it smells like $#@$ in here". I don't say anything, but it's kind of sad because I know it's me, so I pretend nobody ever said anything. My mom's fiancee has noticed it and said it smelled like crap, but I don't think they know it's really me. I brush my teeth, use deodorant, wear expensive cologne, and chew gum, and it hasn't seemed to go away. Please give serious, logical answers