Electric Shock Stabbing in Leg?

I have been having these “Etreamly Sharp Sudden Pains” in the lower part of the back of my thigh, it is just above the back of my knee. It is more towards the right side of the back of my thigh but always in the same area. The pain comes on suddently and is extreamly sharp! Best way I can describe it is that it feels like I’m being suddenly stuck with a long “Electric Charged Pin” deep inside of that area. It comes on quickly and leaves quickly but is almost crippling of that leg. No set pattern I can be standing, sitting, driving a car etc. But when it does happen it is breath taking sudden painful Electric Like and Shocking. Any Ideas.