Remember that you don't have to actually 'hit' your head for a concussion -- a concussion can result from a coup-contre-coup injury that can occur when the brain moves forward and back very quickly inside the skull. These post-concussion injuries have happened to my son as a result of sudden and sharp movement or jarring of his shoulders or neck. He treated these incidents like a new concussion and tried to take the appropriate precautions to minmize recovery time. Good luck and best wishes.