It's Herpes Zoster infection, aka Shingles. 带状疱疹。 Doctors will probably prescribe you Antiviral drugs: Acyclovir 800 mg orally every 4 hours (5 times a day) for 7 to 10 days. Topical acyclovir is used to treat first-time and recurrent mucocutaneous herpes simplex virus infections Or Famciclovir 500 mg ORALLY every 8 hours for 7 days 病好了。别忘了打Shingles Vaccine (Zostavax®) , good for 6 to 10 years. Some pharmacies carry Shingles Vaccine and pharmacist in some states can perform vaccination, fees may be lower than clinics.