I can only speak for myself, but I have been diagnosed with gastritis and can only think that the acid from my stomach is what is making my breath so awful.
When I am feeling that burning in my throat, it also seems that this is when the bad breath is the worst. I always carry gum or mints but sometimes I don't think that is enough. It's not a nice way to live. I wish I had a pleasant breath. I always am feeling like my mouth and throat are not right.
Am sorry this is the same for you.