I seriously think that even though you've had 3 opinions, it is crucial for you to go to a center, like Mayo, and see what they think. I believe that they get many of the hard cases, as they area center that attracts from far and wide.
Since your condition is debilitating, taking the third opinion the last word is not, in my opinion, your best decision. Of course, it's your call, but if it were me I'd be traveling as far as it took to find a solution. There is even John Hopkins, which I've heard is a great center.
Yes, I would definitely explore the malpractice option, although I'm quite sure it will be a very frustrating and stressful path. That said, I am a believer that if you've been wronged, you deserve remuneration, and the satisfaction of being heard.
Still, I would recommend HIGHLY that you search out other experts to take a look and consider what other options there are to help you.
After searching for help in this way, yes, Cat has the very best of advice. Acceptance and gratitude for what is good in your life, in spite of your difficulties, is the best way to achieve happiness.
Get on it. Don't assume that these three doctors are the last word.
I wish you a very successful search.
We're with you!