What is wrong with my back?

Patient: I fell on my coccyx area 1 year and 8 months! My back has been agony ever since! I went to the hospital the next day and they prescribed me diclofenic. Since then I have had an x-ray and it has come back fine. I have had physio and accupuncture and they have not helped at all. I have recently had an MRI scan on my sacrum which they told me over the phone the report is clear, but dr wants to see the images and they gave me an appointment for 3 months time. My back is worse when I have been standing for long periods of time or sitting for long periods. It also hurts to sit on hard surfaces and I have to sit in a particular way so I am not directly on my coccyx. It hurts to bend over. What could be wrong with my back??