I wonder if your answer will lie in the EMG results, because it does sound a lot like like cramp fasciculation syndrome, doesn't it? Especially with the twitching and exercise intolerance. (I'm not a doctor, but did look into this because I've had fasciculations as well). There seems to be treatment options for that, which would be positive.
Have you had a full blood work panel, including levels of vitamins and minerals?
Keep us posted when you get your mri and EMG results back, britmatt!
I am very sorry for all your issues. I sure hope the neurologist can diagnose you. It must be very frustrating.
Alex