My son felt head waves, then his jaw locked open,then he collapsed and convulsed. On the way down he was grabbed to keep him from going overboard,then hit his head,and neck. He has a black eye, and his neck hurts now. He doesn t seem to have any other symptoms. Emergency room mad had his heart monitored, said there is a heart murmur. Referred us to a cardiologist. What could possibly be wrong?