What Causes Severe Pain And Cramp In Inner Thigh Radiating To Groin?

I am training for a body building show and work out 6 days a week. About one month ago I was almost finished and was sitting on a bench waiting for someone to get off the calf machine. When for the first time ever I had a huge cramp in my right leg hamstring but on the inside of my leg close to the grown. I drink between 12 and 17 bottles of 8oz waters. I eat 405 grams of protein, 4000 calories and 1300 carbs. Every since then it still bothers me and if I stand a while and o go to stretch it starts to burn and cramp. Do you know why and what I can do to get better? It makes working that muscle out really tough.