I have learned to trust parents. They know when their child is "not right". Head injuries are a good example. The child may just seem aloof to us, even though they make sense, if the parent tells you, "That's not how he/she behaves", listen. A parent's intuition can really be an awakening. It was to me in the past, and it will be again. While there are "panicked parents" who overstate illness and injury, many don't. Just listen to what they say. Clues, clues, clues!