What has done wonders for me with very similar (but not exactly the same) symptoms, was learning about Auyervedic. I started with Auyervedic cookbooks (one by Amedea Morningstar). They helped guide me away from certain food, that, while considered healthy by many standards, were not right for me. For example I moved away from raw vegetables, certain fibers, (soy-based or other meat substitutes like mushrooms actually triggered my nausea and a few vomiting spells). What has helped tremendously is learning the value of spices (for health, but thankfully for flavor as well).
Check a cookbook out and use them for what works for you. Don't get overwelmed by too much weird or exotic foods. I have 2 Auyervedic cookbooks and I don't use any of their recipes, just the concepts. I make 4-5 small meals each day that consist of about equal amounts vegetable, meat, and grain. I have a 1/2 dozen spices that really help with digestion and flavor, so I am not putting lots of effort into what I cook. It takes me 30 - 45 minutes each morning to make all my meals for the day.
I keep to this diet 80% of the time and feel good when I am maintaining it. I feel the consequences pretty quickly when I veer off course at times. Occasional splurges on inappropriate food don't cause the challenges they used to.
I do also take some supplements to aid digestion (hydrochloric acid, pancreatic enzymes, probiotics, and I drink a tea every evening to manage my gallbladder dysfunction). I have been moving in a positive direction for over a year without "medicines", so I will continue with this until it proves ineffective.
Hope there is something in this that you find helpful!