A subtle neck injury does not always have any pain or stiffness symptoms but still causes problems. That is why it is called subtle. Imaging will not show it unless you have some very specialized imaging and assessment.

The problem is they cause inflammation and interrupt blood flow. This can manifest as a myriad of symptoms. Mine interrupted proper breathing besides causing stressful dreams that meant I would have a foggy brain day.

A PT with very good manipulating skills could tell my neck was messed up. I had subtle problems from C-1 to T-2. X-Rays and CT Scans did not show it. An MRI showed some foraminal narrowing.

Check https://nora.cc/healthcare-locator.html to see if there is a Behavioral Optometrist in your area. There are three different disciplines that look at visual issues, Behavioral Optometry, Neuro Optometry, and Neuro Ophthalmology. Most find better results with Behavioral Optometry.