You may wish to read up on
paresthesia - warning: it has a bunch of causes, it is just a general description of the type of pain you are experiencing.
I would ask an additional question: Is the pain relieved when you hang from a chin-up bar (best way to do this is two use ab slings or a pair of weightlifting belts with your upper arms in the belt, so you're not using main grip strength to hang) for a period of time; say, 5-10 minutes? Or, have you tried any other type of decompression therapy (such as an inversion table)? If so on either question, did it provide relief?