Can be a challenge spotting the symptoms, though - I went to my GP many years ago with "symptoms". The doctor said if the "symptoms" didn't improve I was to go to A&E. They did a load of tests & said it wasn't appendicitis, but a bad attack of Irritable Bowel Syndrome brought on by stress. I quit that job the next day (after 27 years there) & cured my "appendicitis".
But if I got the "symptoms" again, would it be appendicitis or IBS ? Easier to diagnose running problems on bikes that on myself !
Hope your son gets well soon, Jerry.