To dream that you have a concussion (accidental injury to any organ, but especially to head or brain), can be interpreted as symbolism of inability to use your own powers. Maybe you are in situation, where your can’t utilize your fullest potential. Dream about concussion also suggests that you must be more active and need to be more responsive to others. Are you just sitting back and waiting for things to happen without your personal interaction?
Read more about dreaming of Concussion in other dream meanings interpretations.