My poor, sweet Mom had a HORRIBLE case of shingles on her face. Depending on your age, it can be worse. Since she is older, it hit her pretty hard. The more supressed your immune system, the harder it is to fight. Yes, you can have it flair up again. From my understanding, you are now susceptible to it for the rest of your life.
Shingles of the face/head typically effects the 5 nerves that run across the side of your face, only affecting one side. It can cause visual problems when it goes into your eyes, if not treated quickly and effectively.
Sorry... I know this all sounds like gloom and doom. I don't mean for it to! Mom had hers for 2-3 weeks. Very painful! However, she got over it with no damage to the eye (thanks to our wonderful optometrist and physicians.) She does still have some pain at the nerve endings. Go on line to a respectable Medical website and research it. I'm sure you'll find great info. there. Diet and not getting too run down is supposed to help keep it away.