What could cause these symptoms in a child other than diabetes?

clammy skin
sweating
acting out
They go away after he has a snack or meal. The doctors have tested several times for diabetes but all the tests have come up negative.

What Are These Symptoms Of?!??! Help!!! Whoever Answers Well Gets Best Asnwer :d?

OK
lightheaded in temples
dizzy
fast hearbeat
diarrhea
stomach aches
seeing green or yellow sometimes
pain near my heart and armpit
bloated
headaches
hot and cold flashes
excessive hunger like every 5 minutes!!
OK im not diabetic,anemic, i dont have heart diseases of condtion
i eat healthy sometimes…..um………I’ve done bloodwork,allergy tests,ekg,MRI,endoscopy,stomach x-ray,eye exam,heart x-ray chest x-ray (lungs) Cat scan,eeg and………………………………. [...]