Dear Lisa,
Your story is very relatable. While everyone's experience is unique, I went through a difficult time in 2008, when after about a dozen doctors I had no definitive diagnosis or direction from mainstream medicine. I actually had a doctor tell me to go home and pray, which may be good spiritual advice but was a let-down in terms of Western medicine.
I don't know your background or all of your symptoms, but I can glean from this post that you have, at least, paresthesias, balance issues, and fatigue, but not enough clinical evidence that MS is the cause. That is very similar to where I was in 2008.
There is a lot of confusion and misinformation surrounding it, but have you considered Lyme disease? The doctor that finally listened to my health concerns what an internal medicine physician specializing in chronic fatigue and fibromyalgia. He later became a Lyme doctor, because he learned with time that many people labeled as CFS and/or fibro actually have chronic Lyme, a treatable condition.
I'll go out on a limb and suppose that you are 100% certain that you do not/can not have Lyme. If that is the case, then we really do have a lot in common, because I was also certain that chronic Lyme was a made-up disease, and that certainly if I did have Lyme then I would recall a tick bite or I would have tested positive for it.
Despite my skepticism, I had exhausted all other options, and no other doctor was offering a diagnosis of any kind, let alone treatment, so I decided to undergo antibiotics for Lyme. Mind you, at the time I started treatment, I had an abnormal MRI (8 lesions at age 28), constant paresthesias, eye pain and "flashing lights" when I moved my eyes, heat intolerance, relentless fatigue, and more than I can recall or care to write. And my symptoms came/went in a relapse/remit pattern. I was weak as a kitten, was barely holding on to my job (was reduced to part time and using up my leave), and was in constant discomfort if not pain.
To wrap up my story that is becoming longer than I planned: It took a long time, but I responded well to treatment and though I'm not cured completely of all symptoms, I am much much better and back to living life.
If a skeptic like me can look into Lyme, and if a cure is possible, I hope that will help you decide to at least think about it.
Some resources that may interest you: THere is a film that is on Netflix and other stream sites (and probably also YouTube) called "Under Our Skin." There is also an awesome book "Cure Unknown" that is ~$10 for the ebook on amazon, by P Weintraub. She is a scientific writer who went through the same debacle, so the book as a beautiful balance of science, history of Lyme, and personal experience. It was not only her but her entire family who was sick.
There is also a Lyme forum on MedHelp:
http://www.medhelp.org/forums/Lyme-Disease/show/148
And though I don't check this forum often, you can feel free to PM me any questions you have. If you do decide to look into Lyme disease, it is very easy to become overwhelmed and frustrated by the consenting opinions in the medical community and some of the more "out there" patient forums. I know in my case that was a big factor in me dismissing Lyme for as long as I did.
However you decide to pursue your health, I hope you find answers and relief.