What are the syptoms of a mild concussion?

First,: There must be some history of closed head injury which did not result in gross brain injury visible on ct scan or significant loss of consciousness. The person is stunned, may have a headache, nausea, dizziness, and followed by days of poor sleep, concentration, irritability, and maybe persisting dizziness, ringing in the ears, lapses of short term memory. There are more but these are significant.