Found an indent directly on the top center of skull recently. Scalp feels painful to the touch and hair moving around in that area hurts. What is it?

Cranial suture. One possibility- a cranial suture. This is a line formed from the joining of two plates of the skull. There may be a large one you can touch, under your hair. Every skull is a little different. There are also bumps and ridges. These are rarely pathological, but it is not a bad idea for someone to see it in person to learn more.
Needs to be seen. It would be good to have your doctor take a look at it. One thought would be prior trauma/infection (even a year ago) that you just came upon, but it would be good not to assume it's a benign process.