is one of the known causes for abdominal pain
Instead of stopping the dairy 'change the brand of milk and see. Also see whether it is relatedto any particular food,juice ,jelly etcbecause food colours,preservatives can cause allergy like this.Keep a diary and note what she took the day she had pain otherwise we cannot relate.
If latose free has not helped the diagnosis may be wrong.
I can understand your concern as a mother but at the same time be happy that she has nothing major worry about!