Dancer with cramp!? Is my career ending!?!?

Hi, sorry this probably sounds really pathetic but recently I have been having really painful cramp in my calf so much that I can't go to my dance classes and I am crying! It also hurts when I walk!! I have never had cramp like this!! And it has only started the past week or so.. I am a dancer and take my dancing seriously! I am 13 years old and grade 6 in ballet modern and tap and also do alot of disco freestyle. Why am I having this cramp and what are the causes? Thanks for all answers! xx