Hi, Last night I noticed a large red welt at the base of my spine . It doesn t itch , but it does hurt. It s raised, red, hot, and hard--about an inch in diameter. Tonight, there appears to be a black spot in the middle of it. I don t usually get acne on my back, and I ve never had anything like this. I have had spider bites recently, but those typically itch, and this doesn t itch at all. What could this be?