Thank you to EVERYONE who has replied! I wanted to update this thread. My sister finally got an endoscopy and they found out she has ulcers! And not just a small one, but multiple ones, and one is quite large. It was literally like pulling teeth to get any tests run, and the dates to get them were so far out it was insane, weeks to months down the road. She was literally down to eating only 3 foods...artichokes, apricots and things like maple syrup or agave. She couldn't have wheat, soy, any meat, no veggies or other fruits. It was insane. Her GI doctor had a last minute cancellation or he decided to finally believe her that she wasn't making this up, and scheduled the endoscopy, and thus what we discovered.
Anyway, now that she's on the acid reducing for the ulcers, she's able to eat again! We haven't tried things that she was much more sensitive to, like poultry and dairy, but corn, legumes/beans, soy and oils she can now eat again, which is honestly life changing for her.

The crazy part about all of this is that it took my family asking questions, and doing "me-search" to try and figure things out, and EoE, eosinphilitis was one of the only things we had found that might fit, hence why we wanted a referral to Mayo in the first place. If they had actually believed her about not being ABLE to eat vs not WANTING to eat, we would have solved this years ago. She's been having less and less food she could consume for 8+ years, with the last year being an extreme reduction in food rapidly, hence all the tests, dr visits, etc.

Anyway, I appreciate the support from this thread <3 So, that's the update!