What Causes A Foul Smell In The Nose?

I have a problem with my nose please help me. When I breathe through my nose it smells like poop I didn't have it before. I went to an ENT Specialist and had an X-ray the ENT said theres nothing wrong with me. Now I'm afraid to go to school and I'm considering suicide because people keep talking behind my back and it's really frustrating they're so inconsiderate