I used to wear a special bite splint / alignment device thing after I had the misfortune of an accident that messed up my jaw in my teens. To this day, one side of teeth make contact before the other side by just a mm or 2.

My teeth don't grind at night, but the next time I head to the dentist I'll look into seeing if I can have the issue corrected... worth a shot!

Thanks for the suggestion!

Edit for more info:

My wife helps out with back and neck massages, and my traps (neck and between the shoulder blades) usually have knots on the days I have trouble. I plan on ruling out weak traps and other muscular imbalances for good this spring, but as I mentioned in my initial comment, I have had three different rounds of PT sessions with different workout strategies over the last decade, and still no resolution (nor improvement during/after).

This tension thing waxes and wanes just like the other symptoms, but far more frequently.