I have the same problem. I have sometimes gastritis that can last up to 2 weeks where I'm unable to eat coz I feel so sick... I have no acid reflux just a feeling like there is an inflammation in my stomach and that I cannot burp properly. I've been put on Nexium for a year which has done nothing at all! Gavisgone is useless, ranitidine too! there was a time whenthe product Alkalal worked really well but then it did not work anymore, then I tried Regulat, again it helped for a few months then it stopped working. I had endoscopy, colonoscopy, barium eneama, breath test and blood test for H.Pylori... all negatif! Tried gluten free diet, sugar free diet, dairy free diet, FODMAP...you name it! I got so skinny coz I could hardly eat anything that I lost 9 kgs. My Dr thought I was anorexic and most of the time they did not believe that it was the pain that was stopping me from eating. They tried painkiller, anti-depressant (amytryptilline) for the pain, nothing worked!
Since August I have been put on big amounts of laxatives which did help massively, I was able to eat any types of food and gain 6kgs
the gastritis disappeared a lot instead of having it all day I got like 1 a month. But guess what? last week on wednsday it happened again and now I can't get rid of it! so I guess I'm back to square one.
I'm fed up! this pains is unbearable.... it feels like I'm going to be sick anytime but I'm not and if I throw up I usually don't stop so I need 2 injections from the Dr. to stop me from throwing up. A real nightmare
So I do empathy with your pain and problems. It's a nightmare. I am also diagnosed with POTS and chronic Lyme disease so I'm not sure if the other condition is giving me trouble in that department.