Hmmm, I bet it's a bruise. I had a bump show up on my butt cheek out of the blue years ago. It looked like a bug bite but never went away, it was flesh colored, shiny and raised. Convinced myself it was CA. Finally got the nerve to go to the derm, he looked at it and said that's nothing, but I'll remove it if it's bothering you. He removed it, and it was nothing. I bet yours is nothing too! Give it a few days and I bet it goes away.