most babies lose some — or even all — of their hair in the first few months of life. And it’s completely normal. This hair loss is called alopecia, and in babies it can have several triggers, from hormones to sleeping position.

Some more tummy time will stop the rubbing on the back of the head

If she is rubbing the back of her head alot then that’s maybe a reason why though they need alot of tummy time to start there muscle growth

Yep, nothing to worry about, it’s just from spending so much time laying on their back, it grows back