OK not sure if this will help or not, but it might. I was having horrible stomach problems when I was 44, 3 years ago. Could not figure it out, had biopsies and colonoscopy, blood tests, feces tests when I was acute. No one had a clue, colon totally healthy etc.

Turns out, I am allergic to Rye, and Rye alone! No other grain, no lactose intolerance, nothing to do with gluten, just Rye. I haven't eaten anything Rye since the last episode and have had not one problem. Point of my post is maybe, just maybe it's some bizarre allergy like mine that not even Doctors and Specialists can pinpoint. They couldn't for me, I figured it out by racking my brains and using trial and error. Hope your wife gets better.