Hi. I have the same problems, reflux, excessive burping etc. I also get the shoulder, chest, back and arm pain. I have had every test under the sun and I don't have a heart problem. The only thing that I can figure is that it's either trapped gas, or it all caused from stress & tension. Since stress can cause both stomach problems as well as muscle aches & pains, specifically in the neck, chest & shoulders.
One thing I will say is that I have been trying homeopathic methods for treating the Acid Reflux and they seem to work better than any prescriptions I've tried.
If you're game, try mixing a tablespoon of unpastuerized Apple Cider Vinegar, mixed with 4oz of water 1 or 2 times a day. Gulp it down. It tastes like hell, but it really does seem to be helping.
Also trying stretching exercises and massage for helping with the shoulder pain. Maybe even a chiropractic adjustment.
Hope this helps.