You might try asking your doctor to do a breath test for H-pylori. It is a stomach bacteria that causes ulcers, severe reflux, gastritis, cancer, etc. I had the same problem and found that is what I have. My doctor found it in an endoscope with biopsies. I have gone through a 14 day treatment with 4 antibiotics 4 times a day. Truely exhausting. But I go next week to have a breath test to see if the antibiotics killed it or not. I am hoping so, otherwise I will be doing another 2 weeks of antibiotics.
Hope this helps and most importantly feel better soon!