Hand issues

I am touring constantly for a PR group for MVNU...
we had a gig at King's Island and we had just finished our last song when i felt something funny in my picking hand--i picked with my index finger and pulled my arm up and saw that my index and middle fingers had curled up into a ball, my elbow was bent, and i couldnt move/control any muscles below my triceps...i couldnt even straighten my elbow. I freaked out to say the least. Anyway...we had another gig yesterday and my arm started to cramp again near the end of a set when i decided to just pluck with my thumb until it subsided...
has anything like this happened to anyone? Any advice to get past this? I apparently need more endurance for straight 16ths songs...