kremlin, any chance the chest pains are just stress? Basic stress, even without other anxiety symptoms, can certainly cause pressure in the chest. You mentioned acid reflux, which is a big cause of chest pains for me when I'm not sober.
Funny enough, my biggest cause for frequent chest pain is actually my spine. I've had neck and back issues for a long time due to car accidents. A lot of people think chiropractors are snake oil salesman (and a lot of them are), but a good one can be a life saver. If the upper spine, between the shoulder blades, is out of alignment, that pulls on the muscles and all that junk is connected. Now I can fix those pains myself each night with a foam roller. Lay the spine down the length of the foam roller and I hear the crack all the way up. Immediate relief. If your muscles are tight or knotted up, it's very difficult to do though. Maybe consider a deep tissue and give that a shot. Worst case you eliminate a structural issue, but get a massage in the process (not that deep tissue is particularly pleasant lol). Good luck.