First consult doctor. Give her Banana and Curd. Because Banana helps in smoothing process. When a child gulps something by mistake he is advised to have only Bananas for some days till that comes out in stool.
First cut down milk and milk products to some extent. Bcz milk increases constipation in some kid's. Try to give her Honey with Luke warm water in the morning and also give greens simultaneously . Try to keep her hydrated.. I am positive this will help..