Leg pain, how to end it?

Hi guys, i got this nasty leg pain. Before i continue let me first say how it happened, well i am a karateka and as one i must be flexible especially with my legs, so i went on trying some flexiblity exercises and the following day i had pain in my left leg. It does not pain constantly but when i stand on my left leg or cough or sneeze it pains terible i can't lift my right leg too. The exact spot where it pains is the beggining of my leg i mean my hip and my thigh where the meet exacly there. I went to see a doc but he gave me some medicine which did not work. Plz help me because it is one month now.