What Causes Pain In My Groin?

I played football yesterday during the game i felt a slight pain in my groin, I stupidly decided to carry on playing. I kicked the ball while turning and I felt a huge sharp pain in the same place. I had to stop playing as I couldnt run or kick the ball. I can walk on it buts its very painfull. I also have an achy pain in my lower back on the right side (same side as groin pain). I decied to see a doctor but could only be seen by the nurse. She has prescribed me some strong pain killers. When lying flat on the floor I can't lift my leg at all, there is not much pain when i try to lift it, it just wont lift? Also I cant bring my knee up to my chest, when i try i get huge pain deep in my groin and round to my back. I have been told to go to A&E, im not sure if i should?