I am sorry to hear about your medical problems. A concussion can last for weeks or maybe years after the head injury. The symptoms too vary from person to person. Headache, confusion, memory loss, dizziness, nausea vomiting, slurred speech and fatigue are common. Delayed symptoms include depression, irritability, sleep disturbances, seizures, loss of smell etc. A doctor generally looks for focal neurological or generalized neurological symptoms that would show there is a pressure on brain somewhere. In absence of these symptoms and based on the history a diagnosis of concussion is given.
So, what I am basically trying to tell is that you must consult a doctor and get a detailed neuro-psychological assessment. The based on this assessment, your doctor (neurologist or a neuro-psychiatrist) may be able to deal with your concentration issues, anxiety and traumatic brain injury. You also need an eye examination. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.