4 year old abdominal pain on n off since 5 days,all tests normal( blood, urine,xray n ultra sound . what can b the cause of the pain.

Needs further tests: One may have to look into food intolerance, allergies, celiac disease, lactose intolerance to name a few. Hyper acidity, stress are also contributors to abdominal pain. I do not mean to worry you, but there are many causes if the symptoms persist or gets much worse. Associated weight loss, loss of appetite would be concerning.