Shingles is a form of neuropathy. I believe it lives in the dorsal root ganglia in the spinal cord.

It is called Post herpetic neuraglia.
http://www.mayoclinic.com/health/pos...ralgia/DS00277

I have had shingles down my right arm, and I still get pain from it now and then.

It can occur anywhere from the distribution of the chickenpox you had when younger.

I believe it is called a ganglionopathy:
http://www.ehow.com/facts_6388067_ga...uropathy_.html

If you suspect shingles you can have blood work for the titres of the antibodies to the virus. Several ones can be done. I had both simplex and zoster run when I had my shingles because they were in an odd place (usually it is across the torso chest back area). My zoster titres were very high, but simplex low.
So I took antivirals for quite a while, and also during 2 severe pain outbreaks. That was a decade ago.