I Was In A Car Accident In July I Suffered

I was in a car accident In july I suffered a concussion (although no loss of consciousness and GCS score of 15) It has taken months for physical symptoms to improve. However whenever my neck is manipulated in anyway my symptoms return. The other day after being examined by an ortho when I left and went to my car I nearly passed out and it was as if I had smashed my head all over again. It took almost 10 hrs for me to feel better and until the next day before I felt I could drive a car again. Any idea what could be happening?