Foul odor from rectum?

Strange odor leak from rectum.
Recently for last 6 months i experience foul odor coming from
my rectum. Its a worst smell. People notice and they react. ( they cough and do other stuff)
especillay its worst in indoor. i went to the GI several doctors
( colonoscopy , blood test,stool test and all the tests are
normal). I want to know is there any treatment or medicine available

>>1
You remind me of this guy I used to know at university, who would smugly sit in the bar each night with his palmtop computer, writing crap fiction about the lands of elves and dwarves, sipping his cans of Fanta while trying to chat up the barmaid who hated him. He'd stand near her room late at night looking into the window to catch a glimpse. His fat, nerdy form reeked of body odour (he would leave smell trails around the computer science department, which was malodorous anyway) and was pig disgusting.