As Jo*Mar said, I would suspect you have an upper neck injury of the whiplash type. They can cause many symptoms that mirror concussion symptoms without the 'seeing stars' symptom from a head impact. They can also take longer to recover from because people rarely consider the upper neck and go on living as if their neck is fine. I call them subtle neck injuries because they exhibit no symptoms that are specific to the neck.

A gentle chiro like an upper cervical chiro or a PT who can do gentle traction and mobilization and following up with disciplined head and neck posture for a month or two can help. The chiro or PT alone will not help if you do not add the posture disciplines.