What Causes Severe Pain In The Lower Pelvic Area?

Hi,
For the last couple weeks I have been having a very sharpe pain in my lower left pelvic area (it is not in the bone). I am not in pain constantly but it has become a lot more frequent and sharper. I have tried taking some over the counter drugs for pain but nothing is helping. Sometimes the pain is so bad that while I'm walking, I have to stop moving and I bend over in pain...but it only lasts a few seconds. Please help me