Welcome to HCM .
in a child can be due to various reasons like refractive error
, allergic conjunctivitis
or even dry eyes......
If your child changed her glasses recently ( within 1 month period) , then give her some time to get adapted to her new glasses. She can use a lubricant eye drop
just for soothing effect till then.
If the pain is present only on blinking along with itching / burning sensation revisit your eye doctor to rule out ocular allergy and dry eye evaluation to treat her accordingly.
So take care :).