When under stress or emotional upset, I ve started getting dime to quarter sized bumps on my buttocks. It starts out, before the bump forms, as an incredible itch, which, if scratched, burns and is painful. If left alone, the itchy area then develops small clustered blisters that appear to contain pus. These blisters eventually break, and the area heals and goes away. My husband says after the areas heal, they appear to be bruised. I ve been treating the areas with Bacitracin when the itch develops, and sometimes the blisters will wither and heal without breaking. If the blisters break, they appear to seep/drain for about a week. What is this?