Often times when I drink sodas, caffeinated drinks, apple juice, beer, and other liquids, my stomach slowly becomes very acidic , at least thats the best way I can describe it, and I begin to produce a large amount of saliva. If I drank enough of these drinks, I might vomit as I have in the past. The only remedy I ve found besides waiting it out is laying down and sleeping. I ve been trying to pin point what is the cause of this for years but to no avail.