What Causes Severe Chronic Pain In Buttocks Post Injury?

I had heavy fall on to my bottom from a good height hip X-ray are normal no fracture of pubic bone but intense pain in buttocks difficulty walking or lifting leg great pain on sitting and getting up my hospital refuse to X-ray again as looks clear but pain is unbearable and seems to be coming from deep in my seat bones could I go to another hospital and ask them to X-ray as I m certain I have a fracture it now 2 weeks and pain getting worse