Hi, I suddenly (my husband saw it this morning and said it wasn t there the day before) developed a skin lesion on my back, oval, maybe larger than a quarter. It s slightly brownish in the center with a light pink ring around the outside. I have no other symptoms. It doesn t itch or anything but looks alarming. What could it be? ...we stayed the night in a hotel, I wore a second hand dress the evening before, and we were out for New Years in a large dance club with lots of people...so I am wondering if any of those factors may have caused it?