Hmmm, my son was plagued with this problem. They discover he has stage 2 fatty liver disease though he is young and an average weight. He has stopped all PPI and upped his exercise regime and is eating a plant based diet. All foul smelling breathe has resolved!! Best wishes! Hope you get to the root of what is causing yours. I understand that it must be most distressing. Keep searching my impression is that many things can cause it.