Hi – there can be many different types of white marks on the nails (technically called Leukonychia) and many different causes, so I’m going to share this article by Stanford Medicine which characterizes the hand and nails and possible causes for each pattern. Do any of those images look like your daughter’s nails?
If it’s simply white dots and no lines, this could be from nail damage (trauma to the nail, nail picking, nail biting, nail polish, etc), possible fungal infections, and/or nutritional deficiencies like calcium, zinc and a low protein diet.
Does any of this resonate with you?