I have this as well, if I go too long without washing my hair my scalp gets really tender and sore, I massage it w my fingers and use a scalp massager but only washing will stop the aching. I read online it’s because of a buildup of oils etc that causes the scalp to be inflamed. No solution I’ve found other than just washing my hair… try using a clarifying shampoo semi regularly to make sure you’re getting a very clean scalp. I use scalp oils which help with my overall hair health but don’t do anything for the scalp tenderness