My Grandson Is A 2/12 Year Old Twin, Tonite He

My grandson is a 2/12 year old twin, tonite he was sitting at a kids table eating a frozen yogurt when he suddenly started to fall off chair as his eyes rolled back . Fell on floor hit his head on tile before I could catch him. Called 911. He was lethargic for hours. After tests and blood work they couldn't find a problem . He came around back to himself after a couple of hours at the hospital .