I've been searching everywhere online for some info on this. My son is almost 2 1/2 and he has also been waking up in the middle of the night screaming and grabbing his foot. I just assumed it was spasms because I get them alot at night. and I too massaged it and after about a 1/2 hour he fell back asleep.
But his teacher brought it to my attention during school hours and it happened twice there and once with me during the day now.
I made an appointment for tomorrow with his pediatrician. Isn't it horrible to see them scream like that and not be able to help.