Hello ! I understand your concern. Headache is a common sign after head concussion. It may be normal, but it also may be associated with complication like late bleeding to the brain, also called a subdural hemorrhage. Sharp pain at the back of your head is not very typical of a subdural hemorrhage. I would like to know if you have other problems with your gate or nausea or vomiting. If you don t have any other signs , I would recommend just to walk in the Clinic, because no emergency. If you have other signs, I would recommend you to go to Emergence for a brain CT scan, to rule out the complications I mentioned above. Hope to have been helpful! Best wishes, Dr. Abaz Quka