You need to have your doctor provide a SIBO breath test (checks for levels of methane & nitrogen in stomach/duodenum, which can wrongly suggest presence of small intestinal bacteria overgrowth, which can itself cause slow digestive motility & the stomach gas that then results because certain foods, especially those that are highly fermentable, are sitting there). Second, provide a stool sample, which will check for select bacteria in your gut. Because THAT can also point to the same problems & symptoms.
And if your Doc is unwilling or unable to prescribe those 1 tests, find one who can, including (if you can afford; check your insurance) finding a GOOD naturopathic doc.