What Causes Recurring Tremors And Sweating?

Hi my son is 12 years old and will be 13 on Thursday. Twice this year at school I have been called from the nurse s office because of shaking and sweating. The first time this happened he felt better after he ate. I still made an appt. with his pediatrician. Lab results were all within normal limits however the doctor recommended that he eat something every morning to prevent this from happening again. Today the nurse called me and said that he had the same episode. I don t know what to do at this point any suggestions?