A year ago, Grass Valley resident Muffin Latham began to feel a burning sensation on her face. At first she attributed it to recent dental work, but the sensation didn’t go away — in fact, it was getting worse. “The pain was up around my eye, then traveled up to my eyebrow,” she said. “I started to feel like I was burning alive. It was intolerable.” A dentist took one look at Latham — who had developed a severe rash — and sent her to the hospital. Diagnosis? Shingles. Also known as herpes zoster, shingles is a virus that causes …