What Causes Groin Pain Radiating To Legs?

I am experiencing major pain in my right groin, radiating down the inside of my leg. When it is really bad , my entire leg aches. The pain often moves around to the side of my hip. This has been going on now for 4 months.
I have been to a doctor and had an X-ray . It showed nothing. I have been in PT for 3 weeks with no relief.