Suggest Treatment For Itching And Sore On My Back

I have been itchy and sore on the inside of my buttocks. Today I managed to look in the mirror and it looks like blisters which are circled with a white line. It is painful, more like a stinging feeling, but sometimes very itchy. My doctor is away for another 10 days and I'm wondering if I should go to the ER to have it checked out. Any ideas? I am a 60 year old 5'3" female and weigh 180 lbs. I have recently been "dieting" using weight watchers.