I watched a tv show a few years ago about BO. Some people have it due to smelly byproducts of cell metabolism. I haven't read all replies so maybe somebody else mentioned it.
A specialist needs to check this. It's genetic as far as I know. Some people smell like rotting fish (!) due to trimethylamine which is secreted by the body. It has to do with nitrogen. I guess in your case sulphur might be the culprit. I am going to do some more searching and if I find something relevant I'll let you know.