Talk to Gastroenterologist on Stomach Digestion Problem/food Allegy

AoA I’m very in trouble of my intestinal gas expelling (farts) and not doing faece (pakhana) properly mostly in less quantity and feel stress inside belly. My stomach burns when I eat red meat, tea , Restaurants food and other acidic type food now facing mouth ulcers, headache and bad breath. Kindly suggest diagnostic medication Thanks