I actually would get rid of the protein shakes man. They are doing more harm than good. As for a supplement, you can simply start taking apple cider vinegar.
I have chronic acid reflux. Alkaline drops and baking soda in seltzer works, but it's temporary. Alka Setzer GUM is good to keep on you for emergencies. Capsecum helps heal it. CapsiMax. Other than that, there's nasty drugs. They work, but have bad sides.