I had the same experience, after consulting with GI MD and doing some research, as well as coincidentally having a patient with this diagnosis, I was diagnosed with it. Had never even heard of it! Anyway, the cause was likely long term use of omeprazole along with SSRI use. A colonoscopy and biopsy confirmed it. Now on famotidine for GERD, pretty effective at 20-40mg, 2x/day.

Diet: until it resolved with tapered steroids and diet, no greens unless fully cooked, no onions, low-fat, etc. No alcohol or chocolate, etc. Once resolved I reintroduced salads, tomatoes, minimal alcohol and chocolate.

Hope this helps someone ❤️