@lewin Maybe those with a more scientific background are better equipped to answer your question. All that I can think of is the role the gut microbiome plays in both. And they are both caused by inflammation, as you say. An interesting topic to explore, for sure.

I decided to forego drugs when I was diagnosed with psoriatic arthritis (huge swollen hand which eventually caused damaged knuckles). I didn't have GERD or nausea at that time. (I got nausea probably from taking anti-inflammatory pain meds, including aspirin, following a surgery.) The arthritis doesn't appear to be progressing, for now, anyway. I hope you get some answers. Nausea is so terrible. Take care.