@jtbrown John, I understand, Mayo wouldn't be available because of Canadian healthcare. I hope your doctors in Canada can provide some relief for you. Does that limit you in where you can get a surgical opinion or how many opinions you can get?

I do see what you describe which looks like a disc turning into bone between C3 and C4. To my eye, it looks like C4 may be slightly rotated backward which would put pressure in front on the disc above it. Uneven pressure can cause bone to remodel in an attempt to stabilize the spine. I also see what looks like bone spurs on the forward edge of C6. Do you see where that looks rough? I see what looks like some cloudiness in the disc above it. Is that also growing bone? Whiplash injuries can cause spine problems even years later. I had a whiplash that injured my C5/C6 which is common for that type of injury, and 20 years later, my disc herniated and I had bone spurs pushing into my spinal cord. I'm not sure if physical therapy could help prevent discs from ossification if you can maintain proper movement. That might be a question to ask, and of course if you are headed to surgery, there will be a right time to do that after enough healing and authorization from your treating surgeon.

Some people can grow extra bone after a trauma or surgery with a condition called heterotropic ossification. Here is a link to describe it.
https://my.clevelandclinic.org/health/diseases/22596-heterotopic-ossification
This mentions that if you have heterotropic ossification, that it may be related to ankylosing spondylitis. If that is the cause of your bone growth, it is an inflammatory condition that may need some attention to try to stop the progression.
https://my.clevelandclinic.org/health/diseases/ankylosing-spondylitis
Here is a discussion on ankylosing spondylitis where you may meet other member discussion the condition.
Spine Health - "Ankylosing spondylitis: anyone else?"
https://connect.mayoclinic.org/discussion/ankylosing-spondylitis/
Also FYI, please crop off any personal information if you post imaging to protect your identity. You are welcome to post imaging.