The pain your husband is experiencing is called post-herpetic neuralgia, because it occurred after a case of shingles. I have it on the right side of my face/scalp, but was helped after two weeks of attacks that felt like a hot iron pressed against my face and scalp by having my prescription for gabapentin upped to 1800mg a day. When I was on 1200mg, I had the attacks. Does your husband take gabapentin. I don't know if it is mainly for post-herpetic neuralgia of the face or if it helps anywhere on the body.
From Wikipedia:
Postherpetic neuralgia is neuropathic pain that occurs due to damage to a peripheral nerve caused by the reactivation of the varicella zoster virus. PHN is defined as pain in a dermatomal distribution that lasts for at least 90 days after an outbreak of herpes zoster. Several types of pain may occur with PHN including continuous burning pain, episodes of severe shooting or electric-like pain, and a heightened sensitivity to gentle touch which would not otherwise cause pain or to painful stimuli. Wikipedia