What Causes Severe Pain In Hip Radiating To The Leg?

Hi, I have experienced significant pain in the hip area which radiates down the front of my leg. I don t have any limited mobility, can sit and lay down comfortably but walking is excruciating. The left hip where it joins the leg is swollen. This has been going on for 4 days now and ability to walk has gotten worse. I am taking muscle relaxant and just got an Rx for naproxen 600 mg. The urgent care doc thought I may have sprained my iliofemerol ligament. Any help and advice is much appreciated. Is this the correct diagnosis, etc.