Digestive issues have many causes. Sounds like you're being treated for your symptoms. Digestive issues can be caused by bacterial infections (SIBO), fungal infections, yeast infections, parasites, being exposed to mold. Some doctors know how to test for these causes. Ask you doctor.
I had digestive issues, GERD, bloating, gas and treated for my symptoms with Proton Pump Inhibitors (PPI) over the course of 6 years, once off this med my symptoms returned. Within that time frame I had 3 endoscopies. At my last endoscopy, the GI doctor came in and told me to never take the PPI again as my digestive tract cells were hypertrophic. I found a functional medicine doctor who knew how to test and treat. You can find a functional medicine doctor by city and state at ifm.org. Check it out, look for one who specializes in digestive disorders and anything else you may be dealing with. Functional Medicine doctors look for the cause of your symptoms - major difference in treating the cause vs. symptoms.
There is also a great book you can find on Amazon - Super Gut by Dr. William Davis. It is an excellent book to use to start with. In fact, what he recommends is good for everyone whether you have digestive issues or not. Our gut biome needs to be healthy to keep us healthy.
Best to you in finding an answer. I know personally it is not easy but please believe there is an answer. Put yourself in charge if your doctors' recommendations are not helping.