I've had stomach acid issues in the past and have corrected them using betaine HCL. However, I never felt the burning sensation in my stomach either, only in my chest! After a few weeks they helped and now I only take them if I've had an unusually large amount of protein.
As far as what the chest pain could be? I'm sorry I don't have much imput there, but good luck in your search! As long as you keep looking you'll find it eventually.