In reply to FesteringSore:
Go for a second opinion. X-rays do not always reveal fractures, or they may be missed on the assessment. The GP may not be associating the chronic pain with an accident, and may just be thinking 'oh, another bad back...'
Go back to the GP and remind them this is due to a fall, the painkillers are not helping, and request more detailed imaging; CT or MRI. Point out how much the pain is affecting both your lives, and your long-term health. The GP should at least be able to give their explanation for why the pain is not receding after five weeks; bruising ought to be recovering by now. GPs expect you to keep going back if things don't improve, so you have to play the game; they won't pro-actively follow up appointments to make sure things are getting better.
I know someone who fell and hurt their back, went to A&E, and the doctors didn't take an x-ray because their assessment of the injury (by mobility) suggested to them no fracture. Five years of pain later, an orthopaedic consultant went very pale when he heard the answer to the question "and what did the A&E x-ray show...?". It turned out that there was an unresolved fracture, compounded by osteoporosis that a proper interpretation of patient history should have alerted the A&E doctors to... The resulting poor posture to compensate for the pain probably contributed to the need for a hip replacement. All for the cost of an x-ray...
Post edited at 18:19