Cervical issues can certainly be the cause of your issues. I have some of the same symptoms you describe without GERD. I was recently diagnosed with thoracic outlet syndrome. I am a prime candidate for this affliction due to 50 years of throwing a baseball a lot.

Take a look at this website. If you think it explains your symptoms, you might want to mention it to your doctor. Good luck. I really hate that brian fog!
https://mskneurology.com/how-truly-treat-thoracic-outlet-syndrome/