Stomach Cramps What Else Could It Be?

Upper stomach (throwing up) or lower intestines (diarrhea)?
Either way make sure he's well hydrated.
You can go a long time without eating any solid food but you need to keep hydrated and keep the electrolytes balanced otherwise he'll end up in the hospital with an IV.
That he runs around in between tiring out is a good sign.
Was he tested for mono?
Mono can linger a really long time but usually (not always) they are super tired if they have it - the temp can come and go.
My sister had it for most of the 2nd grade (almost a whole year).
Every time she felt better she had a relapse so most of her school work was sent home.
Give him soup broth, pedialyte, Gatorade, ginger ale, plenty of water.
Try to curtail his running around for a week or so and keep him resting, then see how it goes.
When my son has stomach pains, a heating pad or a warm bath makes him feel better.

I dont want to worry you too much... we went through the same thing, and come to find out it was Lyme Disease. 6 Weeks of antibiotics, and my daughter was fine. We went to ER several times, but the Lyme affected her stomach and upper intestine muscles. NO SUGAR regardless. pleanty of chicken broth and pedialite. She was like a brand new kid again. Good Luck.

My son had a virus kind of like this and passed it on to me. It was 10 days of stomach pains that nothing could knock. Not ibuprophin, or even a levsin. I feel for him but it should be over soon. Then watch for family getting the same symptoms. :(

Eat lightly, drink fluids.

Some viruses do last a long time, even weeks, but if they can't identify what virus it is, I'd ask them about possibly testing him for food allergies. His symptoms sound like my friend who has gluten intolerance. If you son has not had it before, be aware that some allergies and intolerances can turn up suddenly even if the person was fine previously eating exactly the same things.

Also, did the blood work look for possible foodborne illnesses? Usually those are more virulent over a much shorter time than what you describe, but it is pretty common that tests for undetermined cramping etc. includes basic testing for E. coli, salmonella and other foodborne illnesses. Again, slim chance due to the time elapsed already, but were those things routinely tested for?

The fact that he is being quite active at times and is not vomiting or having diarrhea would indicate to me that more tests are needed for something other than a virus. And he may need a scan of his bowels to be sure there's nothing going on in there. Do not hesitate to suggest it.

If it continues, bring him to a gastroenterologist.