Unless you only operate a track hoe/excavator, you have spent a lot of time craning your neck in a vibrating vehicle. C-3 to C-7 is where almost all of neck turning mobility comes from.

Add a few concussions that can push the cervical vertebra out of position and you have a perfect storm.

If you sleep with poor posture, these areas can get aggravated and inflammation can reduce vertebral blood flow which can cause concussion like symptoms to manifest. I'd be concerned that you are breathing properly when you sleep. Apnea can make these symptoms worse.

I bet you have a noisy neck when you turn your head when it is quiet. Mine grates and creaks.

It sounds to me like your biggest challenge is going to be learning how to take care of your neck so you can continue to work as long as possible. Being sure that you are getting good blood flow to your brain is just as important. A FitBit can indicate how often you move in your sleep and if your pulse changes. You can get recording pulse ox devices to wear during sleep.

I bring this up because I had a miserable 2 years until I discovered I had developed Central Sleep Apnea (CSA) due to a neck injury that happened with a very mild concussion/whiplash event. The CSA only happened when my neck was is poor posture. About 10 minutes after getting in a poor posture position, my breathing would get interrupted. My wife witnessed me stop breathing 16 times in one hour. She learned to wake me to change positions. When I had these CSA events, my days would be miserable.

Now, my neck is much more stable and I have learned sleep posture disciplines to avoid any CSA episodes.

btw, CSA is when the brain stem fails to tell the lungs to draw a breath.
Obstructive Sleep Apnea is far more common and is when airway tissue obstructs air flow causing snoring and poor breathing.

Do you have some days that are good and some days that are bad with no discernible differences that may trigger the bad days?