Leg cramps for nothing.. boo hoo

Gah... i'm getting cramps lots lately.. Twice while i was in bed (once for each calf on different nights) and once while... while nothing. It just cramped overnight for the whole of next day. I didn't even do any exercise. And one more time was when i did a light jog. All in the space of two weeks. Gosh.. something is wrong with my legs : ( Gotta train the cramps away or something.. wanna do that biathlon thingy.