I've had the same odor you describe for the past four years. Someone on this post claimed that doing kegel exercises to strengthen the pelvic floor muscles had cured him/her of this condition. I've been doing these for about three weeks and it certainly has helped with the incomplete bowel evacuations. My bowel movements are much more solid and complete, and I think it also has helped with the odor. The post didn't say how long it took to cure. I will keep doing the kegel exercises in hopes that the improvement continues.