Has your husband been tested for Lead Poisoning? Or for B vitamin deficiencies?
I have it, too. Some days it is worse than others. My neck is fused from c-3 thru c-7, and my surgeon thinks there is a relationship between my severe whiplash and the PN.
You ever try inversion? I have a friend who found disc problems causing neuropathy were really helped by hanging upside down in a doorway for a couple of minutes a day. I was skeptical but he says it really helps a lot.