This is something that affects many older persons in life, but can strike at any time. The only prerequisite is that you had chicken pox at some time in your life. The following is an explanation written by Mark Hartwig, and used with his permission. One important thing to note is that you should consult your doctor immediately if you think that you have shingles. In fact if you ever have any rash or odd symptom of any kind.
Shingles only occurs in people who have had chicken pox.
When your body fights off chicken pox, it doesn't completely get rid of the virus that caused it. Instead, the virus sort of hides in your nervous system and goes dormant. Later on, the virus can be reactivated and comes out of hiding. When it does, it usually shows up as an itching, blistering skin rash that runs along any one of the body's nerve branches. There may be a long line of these blisters or just a few.