Welcome to healthcare magic,
Your son symptoms are suggestive of appendicitis
but lack of fever/vomiting
can create confusion but appendicitis can present sometimes without fever,so it is better to get it ruled out by an USG and a urine test which will rule out a ureteric colic
and thus can give a more precise diagnosis.Anyways the best way is to get him seen by a surgeon as early as possible.
I hope your queries have been answered well.
Have a healthy life..