P.S. I wanted to add that I know you said it wasn't linked to any foods. However, when a GI system is totally 'irritated' (not in the inflammatory sense, however), it can be a few weeks until you can actually TELL that it's due to a food group. Her system may be reacting to anything and everything at this point. So there is no 'eat-and-be-able-to-tell' what's causing the problem.
Then I assume that gallbladder issues have been ruled out as has H. pylori. Upchuck, as crazy as it sounds, try two exclusion diets. One should be any and all forms of dairy and the other is a gluten-free diet (wheat, barley and rye). There are many people with somewhat 'strange' symptoms who go on to find out that they've actually got food intolerance issues, and celiac is one of the harder to pinpoint. The blood test is, for the most part, not the greatest nor the most reliable test in the world. And the biopsy may not always be correct. An elimination diet will give you an answer as to whether or not it's a problem in her case. But you've got to make sure that no matter which diet she's trying every trace of the possible offending substance is out. There are decent substitues for bread and other 'wheat foods.' It's a few weeks out of her life to give these a try and if it works, it's a lifetime of no GI issues.
The other option is to try a fecal antibody test, which IMO, is a much more reliable test. I'm sure other labs do the test now, but the lab we used was enterolab.com. They have a lot of information on the site that you might want to look at, at some point. My husband had been off gluten for a year by the time we had the test done, but he still showed positive and carries the genetic marker. He's also cross-reactive to casein, the major protein in dairy, so we had to continue to modify his diet. Yes, it was a pain, but the somewhat strange symptoms that he had previously are gone - and he never fit the 'celiac' profile even at his worst.
I have all her medical records and have read and re-read them. All tests come back in the normal range. She has had no bowel changes. Fatigue somewhat but not remarkable. No food allergies ever in family. She had no health problems prior to this change two years ago. Her menstual cycle has been become irregular but not surprised with the weight loss. She doesn't become nauseated- just throws up. No real pain--oh- she has lots of belching just before throwing up usually. GERD has been ruled out- no medications make a difference. She has had Gastric emptying scintigraphy, Barium x ray, Ultrasound, Upper endoscopy and alittle sensor sewn into her esophagus that tracked the activity for 24 hours (can't remeber the test name)
I assume she's been tested for gastroparesis?
Is there any history in your family of food intolerances or celiac issues? Did the report on the upper endoscopy show anything at all? Have you read the biopsy and doc's reports? I know you typically take a doc's word for it when he says 'everything is normal,' but have you read the reports yourself?
I know she's not eating a lot, but did she have bowel habit changes? Any other symptoms however small or odd? Fatigue? Rashes? 'Brain fog?' Tingling in arms or legs? Or?