What Causes Cramps On Playing Sports?

Hi I just turned 16 I'm 5'2 and weigh 120lbs. I get very bad cramps 2 weeks before my period but only when I play sports. The pain is terrible in can't even stand straight but they go away after 5 minutes when I sit out and stop running. I get this about 5 times a year but recently I've gotten them about 1-2 times a week. I also get crAmps when Im on my period but that's normal for me. Is the bad cramps I get from playing sports from my period or is it something else that I should be worried about?