I take Zantac 2x day for acid reflux. I also take Naproxen for torn shoulder things and bone spurs 1x day. I know I am under stress, but I usually handle it very well. Today, my back between my hips and below shoulder blades started hurting and my upper abdomen between navel and under breasts started pain like spasms. I am 56, very over weight, do not smoke or drink. I tried only water today instead of usual diet caffiene free cola, and it continues to bother me. What could this be? Pepto Bismal did not help at all, no bloody bowel movements and no desire to vomit.