Concussion often results in a headache, but headaches due to a concussion will usually diminish with the passage of time. One must be concerned if the headache becomes progressively worse or is accompanied by drowsiness. This may be caused by a hemorrhage between the skull and the brain, and can be life-threatening. After a concussion, there may be temporary changes in mood and attention. Repeated concussions are very serious and can cause progressive changes in the brain.