Thank you Layla.
If it is back pain I hope it is due to my poor posture now. I do find it difficult to keep upright when my legs get tired and knees start to buckle. All my problems seemed to start with my back. The xrays and MRI scan showed arthritic changes in the spine and some flattened discs in the lumbar region, probably age related. A cortico-steroid injection at L5 had no effect at all.
I asked my GP if I could have hip xrays done, which is when a severely arthritic left hip was picked up. This seemed to explain all my symptoms, plus the leg often giving way, causing me to fall. I was so thrilled at the prospect of, eventually, having a stable pain free leg, but now am faced with the prospect of working through recovery from the hip op but still experiencing pain, which originates from my back.