I am exactly the same as you... I cant walk without assistance from a walker and am so dizzy that I want to fall down all the time (luckily I haven't fallen though). It has been just over 4 years for me too. I have been tested for MS, Lyme and many other diseases with all negative results. I have now had maybe 25 infusions of gamma globulin (Gamma Gard) with little benefit. I just returned from Cleveland Clinic (because like you, I have tried many times to get into Mayo Clinic both in MN and FL with no luck). I am now being tested for Parkinson's even though I have very few symptoms. I would really recommend Cleveland Clinic however. I saw 3 doctors while I was there and got listened to at least. Keep me informed of how you are doing.