I read a story...maybe on here...about a mother whose son had no symptoms of concussion other than nausea and vomitting. He went from specialist to specialist for gastric testing. He was lucky finally have a conversation with a resident who was taking routine medical history and clued in to the "minor" concussion he had sustained prior to these symptoms beginning.

This led to ENT assessment and others, found that head injury was root cause of gastric problems.