I'm a newbie here. I have IBS as well as GERD. I've pretty much had the IBS all my life. The GERD showed up a couple of years ago. I've found ways to manage the IBS, so I have that under control, but I can tell you that the GERD has made it worse. Actually, I thought my IBS was acting up when I first got GERD because of the loose bowel movements. I do think the two areas go hand in hand, at least with me.
I just went off all GERD meds as of last Sunday, so we'll see where that leaves me. So far so good. Actually kind of constipated which hasn't happened to me in years.