What could be wrong??

I have been in a toning cl for about 3 months... and it is definetly pretty strenuous! The last couple of days my calve muscles have been really sore, but my left calve is really sore, swollen, and it even hurts when I flex my foot forwards and backwards like you do when you walk. I don't know if I tore a muscle or what??? I am going to go to the doc if it does not get better soon...Any idea what could be wrong?