Sounds a lot like TMAU or a similar condition with sensitivity to different chemicals in your food. Go on a low choline diet. No red meat, no beans, no legumes, no fish, no egg yolk (egg white is fine). If you can then no fried foods, because oily food is rough on your stomach. You will see results within a month. It is possible that your first weeks will be horrible due to the detox.
Don't starve though, because you will get a different Body Odor due to the starvation then. Eat enough calories.