I have a large (about the size of a dime) blister, filled with water, on the outside of my left breast. This has happened before in the same place, but not for about a year. I seriously burned that breast a number of years ago. Could it be from that? When it first starts, it is just an itchy spot, then develops a small red spot, before the blister starts. In the beginning the blister is just small, then gets larger over the next few days. It causes the nipple to be very itchy, also. As the blister gets larger, the itching mostly subsides. Can you give me an idea what it is?