A brief loss of consciousness is very common after a head injury. If you were on a blood thinner like Plavix or coumadin, you might need to get a head CT scan
after the incident. But it has been 4 days and if you do not have signs or symptoms of neurological deficits, then it is probably an over-kill to get a head scan at this time. These are some examples of neurological symptoms that a person might have with a brain injury: visual changes, numbness
or tingling on one part of the body, weakness or lack of sensation on one side of the body. There may not be any significant lesions on the brain scan in head injuries severe enough to cause a loss of consciousness. But there may be some possibilities that there are injuries to the neural circuit at the micro level. Regardless, after such an injury you may expect to have concussive symptoms which can be quite severe sometimes. These symptoms can include headaches, dizziness, poor memory and cognitive symptoms. These symptoms get better over time. When they recur it is important to rest and decrease noise, lights, and other types of stimulation. Your brain just needs a quiet break. Some people may need to take time out from work or school because these activities trigger an attack. I would recommend that you visit a primary care physician
to be properly evaluated.