My Now 3 Year Old Son Has Had Episodes Since

My now 3 year old son has had episodes since he was 1 (totaling 4 so infrequent) where he will tell me his head and/or belly hurt then he will turn completely white (lips and all) lasting anywhere from 30 sec to a couple min. During this time he is completely coherent can speak and answer questions just looks white. Afterwards he generally just wants to sleep. We had an EEG which came back clear.....they r now testing for diabetes but admit it's like finding a needle in a haystack....any thoughts??