Hi. Thanks for your query. Noted the history and understood your concerns. Such momentary severe pain for 4 hours fir two days with interval without symptoms can be definitely worrisome. Vomiting in such incidence can be a reflex phenomenon. Since the child is 12 years old the most probable reason could have been a stone of small size in ureter that passed down to the urinary bladder hence the boy has now no pain, went to school and playing outside. I would advice you to have a clinical evaluation by a Doctor. An ultrasound can be diagnostic. Tests of blood, urine and stool help further. These will hive the exact diagnosis and a plan for treatment if needed as per the findings.