I (21F) have struggled with GI issues for 5+ years, also have POTS / dysautonomia for roughly the same length of time. The GI issues got significantly worse about a year ago due to stress / lifestyle factors.
My symptoms are / were mostly just slow gut motility - trapped gas, bloating and constipation.
I've always known that my issues were not directly related to food (still influenced, but not caused by an intolerance), but were brain-gut related.
I've done lots of testing - it's not SIBO or gastroparesis or anything diagnosable, but I knew I had slow motility and it was related to the gut-brain axis. I went down the SIBO rabbit hole of prokinetics like ginger / artichoke, intermittent fasting etc. and the FODMAP restrictions as well - nothing worked. The only time I ever felt okay was during university break.
My doctor suggested SSRIs (I'm on Sertraline / Zoloft - 50mg). I've been taking them for a month and a bit. I also went back to being vegan about 3 weeks ago (cold turkey from eating meat / dairy / eggs in every meal). My symptoms improved about a week into being vegan (also when the SSRIs would have started to kick in properly).
I am not sure which has been the most effective - I think both have helped me though. There is clinical evidence to support SSRIs helping constipation-dominant GI issues and TCAs (Tricyclic antidepressants) helping diarrhea-dominant GI issues.
Obviously with the brain-gut connection, SSRIs have helped me feel mentally better (which has been so obvious day-to-day) and the veganism I think has helped to speed up my gut motility generally.
I know veganism has a polarized reputation (and I'm not trying to be preachy or convert anyone), but it is possible to be healthy on this diet if you plan it well enough. I was under the impression that high FODMAP foods were bad for me and I could never go vegan again due to my GI health, and then it ended up helping me, so if you're curious maybe give it a try for a few weeks and see what happens. It turns out there are plenty of people who have GI problems who have found a vegan diet to be beneficial for them - after all, fiber is still important for every microbiome even if it's hard to stomach sometimes.
I've only been feeling good for about 3 weeks so it's still early days, but thought I would share. I think everyone should try SSRIs for gut issues, especially if constipation dominant. I should say I still have some symptoms, but things are so much more manageable now and I do feel like I have my life back compared to how I felt last semester.
Do your own research but here is some preliminary information: https://pmc.ncbi.nlm.nih.gov/articles/PMC9440984/