My Granddaughter Is 2, She Has Constipation And Stomach Mostly

my granddaughter is 2, she has constipation and stomach mostly at night. she eats a balanced diet fruit, vegetables and some meat. mostly all organic food. has been tested for celiac disease. also tested for allergy from peanuts etc. she wakes up crying because her stomach hurts with lots of gas but can't have a bowl movement.