choco,
You could be developing restless leg syndrome. Uncontrollable movement or a feeling that you have to move the legs, is a hallmark of this disorder.
Muscle cramps are very common in the lower extremities, especially the feet. If they occur randomly and occasionally, about the only thing you can do is put the muscle on stretch until the cramp resolves.
If it seems that you are developing a lot of cramps, it could be due to an electrolyte imbalance, particularly potassium or sodium. But, this is not really all that common, though it is always listed as a possibility.
So, if the movements and cramps become too much for you to handle, see your physician for an evaluation.
Good luck.