my son does this too and i’m not sure why either, it sounds silly but i wondered if it’s because the feeling of having hair is new to them and they don’t understand what it is, my baby’s has grown really quick and he’s started to get long bits by his ears and i think that’s part of the reason
My daughter does the same, especially the back of her head. I think it’s self soothing too
Maybe get some scratch sleeves from Amazon if your little one scratching and making them bleed my son has eczema so scratch sleeves are amazing to stop him
My daughter has a bit of dry skin and she tends to scratch her head to the point it bleeds. May his scalp itches him. I have started to use cold pressed organic jojoba oil and she hardly scratches her head now.
He could be doing it as a method of self soothing, I’ve definitely heard of babies scratching/rubbing their head for seemingly no reason