Hip and leg pain

[ALGBC]

For two years I have been experiencing severe pain in my left hip which radiates down the leg to the foot, as well as numbness and tingling in both feet and pain in the toes. The pain is worst when sitting down, lying down or bending over, and as a result i stand most of my waking hours. It is suspected to be sciatica,  but I have not been able to obtain a diagnosis, largely because the CT_Scan and MRI of the lower back, which show some minor problems,  show no nerve compression. As well, two nerve block injections have produced no benefit. My question is: How is it possible that I have symptoms of nerve compression, but none is visible in the scans? Can there be another cause?  

Thanks very much.

[ALGBC]

I have tried Gabapentin, and I am currently taking Lyrica, which is a relative of Gabapentin.  It does help a little, but not enough to enable me to sit down longer.

[OldFatChick]

It does sound like nerve pain. Have they tried gabapentin (Neurontin)? It works well for me.