I have had similar problems in the last few years and I am just now starting to see some improvement in my condition. You need to cleanse your colon/intestines. Buy Colosan or Oxypowder to get rid of the waste in your system. Holistic Horizons, Blessed Herbs and Dr. Schulze 's Intestinal Formula are also good products.
What happens is that certain foods get stuck in you intestinal tract and literally rot causing the smell. I was working at a pizza restaurant when mine started. I was eating pizza almost daily and the cheese and wheat stuck in my intestines and caused me to smell horribly. I had to quit that job and move back in with my parents. After cleansing my colon and doing Liver Flushes its almost gone completely.
Stop eating all wheat and dairy products and look up the candida diet and follow it as closely as possible.
Good luck!! it takes patience but people get rid of this problem all the time. Keep your head up