This may possibly be related to your sulfur metabolism, or ammonia metabolism, and genral methylation genetics. I would recommend trying a low sulfur diet; ask your doc about molybdenum supplementation to help body get rid of toxic sulfites . Sometimes, one may have a bacteria growing in the gut, which uses sulfur instead of oxygen (sulfur reducing bacteria), and those seem to respond a combination of Xifaxan and neomycin or Flagyl, I believe. Another issue may be excess ammonia in the blood, also product of amino acid metabolism. May benefit from a lower protein diet...