You die.
Symptoms of a severe concussion, go see a doctor immediately.
It's better to see a doctor in case there may be other complications associated with it.
Currently, it would be much more difficult to find a doctor than here on Earth.
Concussion. Go see your Doctor.
Go to the doctor, this doesn't sound good. You may have some damage there.
go to the doctor
You have bruised your brain.
If you received a blow that caused you to loose consciousness, you need to see a doctor as this could cause a concussion. If you felt fine but later started to get headaches, you should also see a doctor.
You could have a concussion if you've fallen and the back of your head starts to hurt. You need to see a doctor right away under this situation. The back of your head could hurt due to a recent fall and the on set of a concussion. If you've fallen recently it's best to see a doctor.
It could mean that you have a concussion, but i think you should go and see a doctor.
Death
Go see a doctor right away. That's a pretty serious concussion in which massive head trauma had caused a hemorrhage in the brain, or in simpler terms, your brain may be bleeding.