I have been wondering if you have tried Lidoderm patches?

Applied to your back, where you know you have that problem, might be helpful for you.

I found for myself when I had terrible thigh pain..called Meralgia paresthetica, from my abdominal surgery, nothing helped it.
Then Lidoderms were approved here in US and I got my doctor to give me an RX for them. Two weeks of very day use (12 hrs on 12 hrs off) and these patches actually put me into a remission!
I guess the nerve was just firing because it couldn't turn itself off. (cutaneous lateral femoral nerve)
I found that applying them at the high point of the thigh where the nerve exists the abdomen was the best spot. I think Lidoderms work best where the "source" of the pain is and not where it is "felt".. which is typically a referral location and not the direct target.

So I think you should try this. They are expensive if insurance won't cover them, but really they were amazingly helpful for me.