Hi and welcome to NeuroTalk. PCS is problematic for doctors to diagnose medically since mTBI will often not show up on a CT or MRI. I agree with Shez, a neurologist would be best; I'd inquire whether they do a lot with work with mTBI patients, as there has been varying degrees of satisfaction from NT members in regards to diagnosis and treatment from neurologists.
Tell us a little bit more on which symptoms are presenting, and we can better support your question based on the collective experiences of the forum contributors.
Meanwhile hopefully this link will be helpful.
http://www.brainline.org/landing_pag...iagnosing.html
Best to you.