Have they checked you for:
Pancreatitis?
Liver disease? (not just your numbers, but looked at your liver)
Checked your common bile duct for "sludge" or bile stones? (your liver can still produce bile stones/sludge after your gallbladder has been removed)
Ulcers?
H.Pylori? (which can cause ulcers, but for me, it "just" caused nausea and stomach pain- after treatment, the issues were 99% gone).
Those are my suggestions, I hope you get some relief soon!