I forgot to mention that my GERD seemed to be related to MS "hug" which is like a spasm in my gut. I have seen that GABA is the nerve spasm relaxer, they give to release snerve spasms.
Although I still get gut cramping, I had a spasm in my stomach and gut that lasted over 3 years that was just deemed a normal part of MS that has since relaxed sporadically , because I take a lot of GABA. It still gets attacked by my MS, GERD is not hone, but my girdle is less tight....

I only put this out there because there's so many exacerbating factors and causes to GERD.

GABA, dopamine, vitamin D and thyroid hormones (aldo iodine), neurotransmitters, electrolytes minerals and salts,
Diet allergens, enzymes, genetics,
So many possibilities.....
Good luck