I'm sorry about all the scary tests
I think I'm in kind of the same boat - I had instability, serious fatigue (don't know if this one's relavent here), and then month-long persistent numbess. I got pretty freaked out... but, well, for the last couple of months I've had these constant crazy visual symptoms - halos, vision ghosts, the world is always sparkly and there are these swirling patches of color. It's pretty trippy - but, well, turns out it's just a persistent aura! I used to get these kind of symptoms only before migraines, but now the migraines come and go, but the aura never lets up.
I haven't really talked this out with doctors, but I've been thinking - maybe the freaky-weird numbness from a few months back, along with the stumbles, were actually just a weird persistent aura? My numbness/unbalance wasn't really tied to migraines headaches either, schedule-wise - but, I think it makes total sense. It's good that you're getting all the tests, just to be really sure, but I've definitely heard of migraines causing non-head-pain symptoms (and experienced them!) and hopefully what you're going through is just a strange brand of migraine. Hope it all works out!