Sudden food aggression

Does anyone have any advice for sudden food aggression? Like Saturday at supper he was fine and Sunday breakfast he was going for blood on my hands. He’s been to the vet and got a perfect bill of health and he’s 4 months old. I’ve never taken food from him, just traded for rocks etc that he shouldn’t eat. He’ll eat treats from my hands gently but once I get near a bowl it’s game on. He started growling and snapping, but today there was no warning and I just got bit on the finger trying to put his food out