So my DD is 3 months old and whilst changing her after a bath just, I noticed that there was a large pale patch of skin across her tummy.. It wasn't there before and I have only just noticed it, I thought maybe it's a birth mark but arnt they darker? I've just relooked through all photos where she hasn't got clothing on and there definately wasn't this pale patch of skin there before.. any ideas on what this could be?