Dealing with infectious gastroenterocolitis

I could really use some help here; any advice would be appreciated.
I’m 38. For context, I’ve been taking something like Prilosec occasionally for a month or two at a time for a few years to deal with mild heartburn. Then, about two years ago, out of nowhere, I started getting hit with nausea, one or two bouts of vomiting, followed by watery diarrhea that lasts until late at night. My temp hits about 99°F. I get some mild cramping, and then it's all over within 12 hours. My family calls it "stomach flu," suggests a bland diet for a few days, and I'm fine. That was the pattern for a while, and then I forgot about it.
Then, 3-4 months later, the whole thing repeats and lasts a single day. It happened again around New Year's.
I went for lab work—everything came back normal, including stool cultures and testing for enterovirus and Rotavirus. All negative. So, I feel deathly ill for a few hours and then it just stops. I saw a private gastroenterologist who didn't think much of it, but he did order an endoscopy and colonoscopy, which I had done in January '22. Colonoscopy was fine, aside from some second-degree hemorrhoids. Endoscopy showed some minor erosions (non-bleeding) and a lot of acid. They took two biopsies; everything was clear except for mild gastritis, and it was negative for HB. I was put on Esomeprazole 2 x40mg for a month.
I finished the treatment a few days ago. Last night, it happened again: nausea, one vomit, then diarrhea, and by this morning, it was gone.

Now my gastroenterologist is telling me it's just more stomach flu and isn't suggesting any further testing. Basically, my gastroenterocolitis keeps coming back every 3-4 months. The stool is watery, no blood, maybe a little mucus. Blood tests are always normal. Once I recover, this nightmare passes, and I'm left wondering who to talk to or what to do to actually find the root cause of these recurrences.
I read somewhere that long-term use of PPIs like Prilosec might cause infectious gastroenterocolitis, which makes sense since lowering stomach acid could let viruses thrive. One doctor doesn't think it's SIBO (small intestinal bacterial overgrowth)—which is hard to prove anyway—but I don't see how that fits since I have vomiting. Has anyone dealt with anything similar?

Sounds like someone else had a similar experience... Just a suggestion... Maria Fisher46

Was a random biopsy performed during the colonoscopy?

Maria Fisher46 said:Did they take any random biopsies during the colonoscopy?

No biopsy was done during the procedure. The report shows a small anal fissure at the 12 o'clock position and second-degree hemorrhoids. They reached the terminal ileum with the scope, and everything else looks normal...

Forgot to mention that the intestinal pass study was normal, the irigography came back clear, and my fecal calprotectin levels are right within the normal range

Are there specific inflammatory markers being tracked during the diarrhea episodes? Was a stool cytology performed? Did they take a duodenal biopsy? Also, can you pinpoint any connection between these symptoms and certain foods?

As of right now—meaning tomorrow morning—I’m pulling my labs. CRP, white blood cell count, and sedimentation are all normal; everything looks fine there. Occult blood test came back negative. They took biopsies from both the antrum and the duodenum. Diagnosis is Grade 1 GERD (I'll post the full results later). Biopsy was negative for H. pylori. I haven't done a stool cytology yet. I can't pin this on anything I've eaten, but the only pattern I see is that it flares up right when I stop taking Esomeprazole or switch over to Nexium...

The only constant thread in this entire situation is the PPI usage. It might actually make sense to run a stool cytology test. As a next step, to rule out whether these diarrhea episodes are linked to the medication, you should discuss stopping the PPI with your gastroenterologist and then monitor how things progress. If the episodes stop, the mystery is solved.

I’ve agreed with my gastroenterologist to stop taking my PPI, though he’s convinced the PPI isn't the culprit. He thinks I'm just dealing with IBS. Personally, I don't buy it—you don't get this kind of vomiting from IBS, and we both know it. When I brought up getting a stool cytology test, he just brushed me off, saying I'd already done the work. As far as I recall, I've had tests for bacteria, viruses, and parasites, but nothing else. Can anyone explain what a stool cytology actually looks at? What are they looking for specifically?

Paul Ramirez59 said:I’ve stopped taking my PPI after talking things over with my gastroenterologist, though he’s skeptical about the link to the medication. He’s leaning toward Irritable Bowel Syndrome instead. The thing is, I don't get this vomiting with IBS—we both know that—but he isn't budging. When I brought up a stool cytology test, he just brushed it off, saying I'd already done it. From what I recall, I had tests for bacteria, viruses, and parasites. Can anyone explain what a stool cytology actually looks for? What are they looking at under the lens?

It basically checks for the presence of inflammatory cells under the microscope.

Here we go again. It starts with mild nausea, then moves to loose stools, eventually turning watery, and finishes with one bout of vomiting. Over the last few months, I’ve done two or three stool samples checking for bacteria, parasites, and fungi. Every single time, they find high levels of Candida. My gastroenterologist just brushed it off, claiming everyone has it. He ran a genetic test for lactose intolerance—negative. He’s still insisting it's just IBS. When I tell him I deal with vomiting, he tells me I do! One thing I've noticed: the bloating and gas really ramp up whenever I eat potatoes, anything potato-based, bananas, or apples... I don't know if that's a coincidence or what. I'm at a loss here. Should I see an infectious disease specialist about this Candida stuff? It's the only thing that's actually been proven so far. I stopped taking PPIs, but it keeps happening anyway.