This is beyond frustrating and I know from personal experience. As others have suggested stay vigilant, seek medical care from a major medical teaching hospital if possible, call daily to whatever MD office you need to and remind them you'll take any cancellation appointment and just become like a dog with a bone, as I describe myself. If you have the finances pay for a concierge doctor. After 5 Er visits and 2 hospital stays I finally got a diagnosis. I would not leave the MD office until I was confident that no other diagnostic tests were available to me. Luckily this nice MD listened to me, told me there was one additional test that could be done and that is when I received my diagnosis. Unfortunately we really need to be stewards for our care and keep pushing the practitioners for answers. Good luck to you!