I have similar issues with pain in my left leg. I have joint facet syndrome in the L3-L5 region and I get Radio Frequency Ablations done every 6 to 8 months or so. Basically the burn the nerve with sound so that the message doesn't get back to the brain. Neurontin and its sister Lyrica are awful drugs. I gained 50 pounds on Neurontin and am much happier off it. Cymbalta also did nothing for me.
I sympathize...it really does hurt and none of the pain meds in the world will touch it. I also take muscle relaxants so that the glute muscles don't contract around my sciatic nerve causing more pain. So far, it has helped tremendously. Much better than the pain meds and Neurontin.
Good luck with finding a solution. A nerve block may be what you need.