I'm having the exact same problem for the last couple of weeks. The doctor thinks it's gastritis. (I was diagnosed with gastritis after an upper endoscope last year). The doctor wants me to take PPI or Pepcid. I tried the pepcid and it gave it terrible constipation and an extremely dry mouth. Then I tried Prevacid, (2 days) made pain worse, now I feel it in my back. bloating, gas, dry mouth, nauseous, fatigue.
Last year I was given Nexium and Prilosec with same symptoms stopped taking it after 3 days.
I'm at a loss as to what to try next. I'm going for an ultrasound tomorrow to see if anything else is going on. Have you been taking anything for it?