I have a 16 month old toddler and she keeps on slapping herself on her head.

She is usually sweet and caring, but also can be a little monkey 😂 this is all new and I feel awful like I'm a bad parent! She seems to be bothered about something recently and I'm not sure what. She does have more teeth coming through but I don't know if that's the reason! Anyone else know why toddlers do this?