Once you have had chickenpox, the virus lives in your spine forever.

It can be activated, and give pain only... not always blisters up.
Low immune functions, stress often trigger it. Cold will make the virus dormant again.

Also diet high in arginine containing foods supplies the virus with its fuel to reproduce. So some people follow a careful diet to keep lysine higher than arginine. You can also take lysine supplements..they are very inexpensive. 2 grams a day to start is about average. Lysine suppresses this replication and the virus then goes dormant again. However, some people develop post herpetic neuralgia, as the virus can damage the dorsal roots along the spine, where it lives. A blood test for the antibody titres of Herpes zoster will show high if the virus is active.

Here is the food chart:
http://www.herpes.com/Nutrition.shtml

As a living example I used to see nursing home patients with bedsores get Arginine in a powder to mix with water and drink, to help the sores heal. Within 2 weeks of starting Arginaid, they'd have a shingles attack!

People who cannot tolerate cold therapy should investigate RSD (CRPS). We have a forum for that.
http://neurotalk.psychcentral.com/forum21.html