Hoping you get well soon and figure this out. Have you heard of the inter abdominal pressure theory for acid reflux, which you’re describing or a theory like Chris Kresser’s?

https://chriskresser.com/how-to-cure-gerd-without-medication...

It’s a fantastic write up, that I read through when going through something similar. For me, ultimately it was controlling my weight (I’m at 12% body fat now) and tons of fiber. I feel like my case was mild though.