Hi, I am an American Board Certified Neurologist with experience in diagnosing & treating all neurological and all other medical conditions including the concerns of Post Concussion Syndrome you have mentioned here, and I am very glad to help you with your health concerns. The earlier expert has opted-out from this question and the company had made this question available to other experts too now.
Coming to the discussion;
What I see that you are suffering from post-concussion syndrome for many years
Most of the post-concussion syndrome cases recover within few months to couple of years
But you are having lots of cognitive dysfunction and it has been going on since year 2009
If it is going to improve by itself then by this time you should have already recovered but you are still having so many bothersome symptoms implies this is unlikely to improve on its own
This means we need to try some treatments to help you to resolve this unfortunate health situation
There are two types of recommendations I will make here to help you with resolving this health situation;
1) If you have not already tried then try to use some brain nutritional supplements like Metanx (which is a combination of active forms of vitamin B12, Folate, and Vit B6) and this can help in improving your cognitive functioning. In addition to this you may also try certain other brain supplements like ALA (Alpha lipoic acid), Acetyl L Carnitine, CoQ 10 etc. All these nutritional brain supplements can help you in improving your cognitive functioning
2) Another recommendation is to try a special treatment called as Perispinal Etanarcept.
This is a special treatment that can tremendously help patients who have history of head injuries and post-concussion syndrome in the form of persistent cognitive dysfunction.
Below I will provide you a web link related to this treatment;
This is another web link to the above mentioned Institute of Neurological Recovery (for conditions like post head injuries); http://www.nrimed.com/
The above site will explain you in detail about this special treatment that can enormously help in resolving your cognitive dysfunctioning and improve your memory, focus, concentration, reduce confusion, and help with all aspects of cognitive improvements, and this treatment can help in improving the annoying vertigo too.
Please let me know if you have any further questions, and if you feel you have received the answer to your question please rate me to credit for the time and effort put by me in answering your question.