A bad smell is coming from my ( butt or anus ) .i even don't know why it is coming.i have gone to many doctors.like 2-skin specialist, gastrologist ,anal related doctor and done many test,endoscopy, stomach ultrasound not anything found please help?

It may be important to wash or clean after bowel movement and bath daily to improve the bacteria in the anus that could cause smell. It is also possible that the bacteria in your bowel may be causing the smell and the type of bacteria in your bowel is modulated by your diet. You may want to pay attention to your diet to cut down on sugary foods, dairy and beans; increase vegetable intake.

Your testing is reassuring that you have no anorectal pathology. Normal skin bacteria do react with moisture around your anus and can produce certain odors. Try avoiding moisture there by not wearing tight jeans or tight underwear. Wear white cotton underwear. Apply medicated body powder.