Is this a symptom of MS?
I'm always off balance feeling, but not actually physically off balance. Once before when I was shaking a bottle of nail polish, I felt waves of almost painless shocks going through my body and just recently I discovered that if I stand on one leg and lightly bounce up and down it feels like the floor is dropping beneath me and I'm falling over and my heart skips a beat because I think I'm falling. Been told its anxiety but not convinced.
Hi
, in short, it could be, but it could likely be a number of things. I definitely recommend talking to a different doctor. 2nd (and even more) opinions can be critical when trying to be diagnosed. 
I
, I agree with Devin and would add that it sounds a bit like an inner ear disorder. You'll likely hear the term vestibular disorder if you pursue this with neurologists and ear specialists. It can cause weird sensations including those you've described. My brother is dealing with this as a possible dx, so it's in the front of my thoughts lately. Hope you can find some answers and relief very soon! Thinking of you, Kim, moderator
