I would seek a NP exam. Have you had one already? NP exams I understand are quite expensive so if you have your own insurnace they should cover at least one due to your accident. I would think that is the best way to see how your brain is functioning. Did you hit your head or whiplash? MRI of neck at all?

Are you seeing neurologist? Is there a headache specialist in your area? Usually a neurologist but need to see one who understands PCS and mtbi. Trust me you need to treat with someone who takes your situation seriously