Since I just found out that my elderly grandmother has this, I had to look online for what exactly it is... from www.mayoclinic.com
Unfortunately it is acutely painful for 3 to 5 weeks and after the rash is gone, skin can still be painful for months. I pray that God's Will is for her to recover quickly.

Causes:
Shingles is a second eruption of the varicella-zoster virus — the same virus that causes chickenpox.

Varicella-zoster is part of a group of viruses called herpes viruses, which includes the viruses that cause cold sores and genital herpes. Many of these viruses can lie hidden in your nervous system after an initial infection and remain inactive for years before causing another infection.

Anyone who's had chickenpox may develop shingles. If your immune system doesn't destroy the entire virus during the initial infection, the remaining virus can enter your nervous system and lie hidden for years. Eventually, it may reactivate and travel along nerve pathways to your skin — producing the shingles.

The reason for the encore is unclear. But it may be due to lowered immunity to infections as you grow older. Shingles is more common in older adults and in those who have weak immune systems.
Definition:
Shingles is a viral infection that causes a painful rash. Also known as herpes zoster, it often appears as a band of blisters that wraps from the middle of your back around one side of your chest to your breastbone. Other parts of your body can be involved as well, including your neck, face or scalp.

The pain of shingles can be excruciating, and the cause might not be immediately evident. But once the telltale rash and blisters start on one side of your body, it's more easily identified as shingles.

Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox. After you've had chickenpox, the virus lies inactive (dormant) in your nerves. Years later, the virus may reactivate as shingles.

Shingles isn't a life-threatening condition, but it can be very painful. Sometimes, the rash leads to a debilitating complication called postherpetic neuralgia. This condition causes the skin to remain painful and sensitive to touch for months or even years after the rash clears up.

Vaccines can help reduce the risk of shingles, while early treatment can help shorten a shingles infection and minimize the chance of complications.