I DITTO what Jo*mar has posted.

Your neck should be considered.

For many, the neck will manifest no testable/imageable irregularities.

The proof is when the upper neck is treated like it is injured and unstable with 24/7 discipline, it can start to improve and symptoms can reduce.

You sound like me in 2002. I was still struggling from an injury Jan of 2001. When I started treating my neck as the point of the injury, improvements slowly came.

The dr's diagnosis of concussion was likely based on your subjective complaints and the mechanism of injury. Those are usually just 'shot in the dark' diagnoses. Anybody who hits their head and tells the doctor they hit their head and do not feel good will get a concussion diagnosis, even if the injury is just whiplash.