I've done the same thing.....and it's usually my left leg. The same leg that gives me fits with spasticity at night.

My son gave me some suggestions that he learned in his police training. I guess they have instances where they have to remain standing for long periods of time. Or remain very still while standing. He said if I'd bend my knees ever so slightly it would help. Well, I tried it and lo and behold it worked! Wedding coordinators tell this trick to the attendants who have to stand for the entire wedding ceremony. Depending on your religion or customs that could be a l-o-n-g time.

I still can't stand for really long periods of time without moving my legs or stretching them but this helps, for instance, while waiting in line or standing at the sink.