Who Said I Have a Hard Head?

So...Thursday night as I sat down on the couch I noticed a very sore spot on the back of my head. At first I thought the obvious: zit. But no. I poked and prodded for about fifteen minutes and still could not find any kind of peak. I started to worry. It was located at the base of my skull. Was I hit over the head with a metal bar recently? Did I have any major head traumas? This wasn't just a sore spot. It felt a bit soft, and HURT. Like an external, isolated headache. I felt that if I shaved the back of my head and looked in the mirror that I would see a horrible bruise. Glenn checked it out and didn't see anything out of the ordinary. Do people sporadically get 'sore spots'? It was suggested that maybe I hit my head on my headboard in the middle of the night and I'm just now feeling it. It's odd, I've felt it from Thursday night until just now. All weekend I kept checking it: yuppers, still sore. Most of the time I kept looking at my hand to see if there was blood. Any ideas?