It sounds as though your doctors have been very thorough in their search for a diagnosis for you. Heading to Mayo’s an excellent idea when you’ve run through all of your options with no answers.
Mayo Rochester is my home away from home so I hope you get in soon and can finally get to the bottom of things. Twenty is way to young to be feeling this sick all the time. You have a lot of living yet to do and need to get back to good health!
If you need any info for travel or lodging in Rochester don’t hesitate ask. It’s a smaller city, very easy to navigate with tons of hotel accommodations. Are you near Rochester?