Has anyone had more than one outbreak of shingles? My doctor says it is rare.

I have a small patch of shingles (about the size of a half dollar) on my right shoulder blade. It has flared up probably about 8-10 times the last 6 years. It seems to happen when my immune system is low or I'm under stress. I just recently finished taking prednisone and 2 days later it showed up again. I too have heard that it's rare to have shingles come back so often. I have wondered why this is happening to me. Please post anything you find out about yours. Thanks!