I have this problem as well sometimes. Basically it seems to be intestinal gas caused by being treating with way too man Antibiotics that have possibly killed off the healthy bacteria in my gut that control the organisms that make the oder. I have used chlorophyll pills and activated charcoal and they work somewhat. My doctor turned me on to using Gas-Ex which cuts down on the volume of intestinal gas. If the gas has bad oder then add a small amount of Pepto Bismal and it eliminates the oder. I have had way too many Antibiotics in my life, so I believe that my good gut bacteria has been compromised. I am considering a Fecal Transplant from a healthy donor, but it is difficult to find an entirely healthy person without a lot of very expensive testing, and I worry about picking up sometime even worse if i don't pay for tests. Most people who opt for a Fecal Transplant first extensively test the donor's fecal matter. It is an expensive process, but in some cases it may be paid by MediCal.