I Am 55. I Was Woken Up In The Night

I am 55. I was woken up in the night with Extream (10) pain in my left leg just below my calf on the inside. It went away in a few seconds, yet hapend 4 times that night. Since then ( 2 weeks ) I have had a few times when I could feel it coming on again in the day, but when I move my leg it goes away. It doesn't happen when I'm moving. Usually when I'm still and my leg is bent. What do you think ? Thank You So Much , J. Dean