Last evening I suddenly experienced pain on the left side on top of my head. It was not a headache feeling, but more like tender and pain to the touch. It was also more soft to the touch. Nothing preceded this. It lasted about 3 - 5 minutes. This morning when I touch it, it is tender to the touch like I had bruised it. I have not had any injuries to the head, and nothing unusual was happening at the time. What do you think?