I am still a mystery diagnosis, but take IVIG.. All I can say is I know how you feel!! I felt like I was going to drop dead, and no one was trying anything to treat me.. they kept running test after test, but it would take a while for those to return, and they would be negative, and then they'd run more.. meanwhile I was decompensating.. Finally I couldn't breathe and they admitted me for IVIG...

I too lost weight, ,but I had awful GI issues.. they preceded the neurological symptoms.. I was getting worked up by a GI dr when I told them my knee felt floppy, I can't smile anymore - my face didnt' work, and my hands felt funny.. they thought vitamin deficiency, but besides Vit D, all else was normal (well I was b6 toxic).. Anyhow I get awful pain in the left upper quadrant of my stomach (below my ribs).. everytime it flares, i feel awful pain and then the rest of the fun starts.. My scopes from GI showed gastritis and esophagitis, but that didnt 'explain the malabsorption issue.. they thought maybe crohns.... then a few weeks ago my sibling was diagnosed with crohns.. so I may have that - who knows!! IVIG helps it though, and "fixed" it for months after the first loading dose