I Have A Tender Red Bump On My Scalp And

I have a tender red bump on my scalp and I don't recall hitting my head at all! What felt like a little pimple now looks like a yellow scab. It is tender but isn't bleeding or anything. I had great full body skin check in January and scalp was great. Is this anything common or should I be concerned? I go to doctors regularly and monitor my health so I want to make sure this is ok. Thank you!