It's possible you have bile acid gastritis which does not respond to typical PPI treatment. It can cause all of the symptoms you mention. Colestipol and the like are bile binders that activate in your intestine and typically cause chronic diarrhea and fat malabsorption. They will not bind with bile acid in your stomach. When you condensed your diet to bland and non-fatty foods it would have felt better from that. I had a bad stomach ache and pain when I learned I had stones and sludge in my duct and bladder so I had emergency gallbladder surgery. But after that I still had an upset stomach when I was really hoping it would stop it. Eventually it died down on its own but they did order a test called an MRCP to make sure there were no remaining issues with the duct. Given you've had these symptoms well before your gallbladder was taken out, I wouldn't think this is a post surgery issue. It's just sad the gallbladder wasn't what was causing you misery. I do get bad stomach aches after eating. I take Mirtazapine as an appetite stimulant ironically. I wonder if you notice you're hungrier than usual.