There are many past threads with related topics.
Have you have any down time, resting quiet time after the accident?
Any quality PT for the neck & to check spinal alignment?
Even upper cervical adjusting might be needed , it doesn't take much to misalign the c 1,c2.

You can use our search tool with specific key words to find past info & we have a lot of info in the sticky threads section -above on the pcs,tbi page.
https://www.neurotalk.org/search.php

If you can tell more about the injury , side hit , top of head, car accident, fall & hit on ground etc..might give clues for best suggestions..