Not sure how your IBS deals with fiber (mine hates it) but that could speed things up, as well as pre/probiotics

Bro just from what I know GI docs love putting people on stuff like omeprazole, it’s their answer to everything lol. PPIs and ant-acute will make your motility worse because you need acid to breakdown food and initiate peristalsis. Idk your specific situation, but I was having reflux and silent reflux, I started taking betaine hcl, so helpful. Try it, can’t hurt you if u take it and have problems just take a couple tums it’ll neutralize the acid. The lower esophageal sphincter closes at a very specific pH so if it’s too high, meaning basic it won’t close, same with too low, that’s one of the main causes of reflux