It's probably hair growth.
I always get aches on my scalp when my hair is growing. I would feel that throbbing and then a week later notice a bump of hair. I think this was when my hair is growing really fast, it happens like every 2-3 months so, sometimes once a month. I know when I get those aches I get like an inch in a month, its pretty crazy. I always thought it was funny how sometimes I would "need" another perm after 2 weeks because I had an entire 1/2 in (stretched) of NG come in.
If you don't have a scalp condition, and you aren't in braids or doing any extra tight wrapping or heavy manipulation, I would wait around and see if you notice a lot of new hair coming in in the near future.