Does The Cortisone Injection Cause Severe Pain In The Groin?

I have been having pain in my groin area, had x-rays and MRI that only revealed a little flouid buildup, have been on diclofenac sod 75 mg twice/day, the meds help a little, but if I turn my leg a certain way it really hurts, plus I cannot walk for exercise without lots of pain, I am scheduled Wed for cortizone injection in groin which will be guided by x-ray, how painful will this be and what can I expect and will the injection actually be in the groin or hip? Thanks