I have this feces/poop smell coing from my anus/rectum.

i have this smell coming from my anus/rectum area. it only happens at school and sometimes at my house. the odor smells like poop/feces. sometimes i cant smell it but others around me notce it. it started about 2 years ago. i eat fast but then tried to eat slower and the smell decreased a little. i shower all the time and make sure to clean my anus/rectum area everyday. becase of this smell  have become a very nervous person around others. im tired of this becasue its such a big distraction for me becuase im always thinking if im smelling or not. someone please help me!!!