Have you tried Lyrica? It has worked for my nerve pain and also is prescribed (on label)for shingles!
Have you tried Nature's Rite Shingles Relief? It works for Shingles and PHN. My dad used it and he said it really worked for him. He was kind of wary at first because I bought it offline for him but it seems to have gotten rid of his pain. It's worth a shot
Can you give a list of what you have tried?