I Have Excessive Belching And Acid Reflux With A Swollen

I have excessive belching and acid reflux with a swollen abdomen. I take OTC Prevacid--two tablets twice a day. I have constant gas and bloating. Sometimes, it is so bad, I get a tightness in my chest. I have had a colonoscopy and endoscopy that shows irritation in my stomach. I have had my gallbladder removed and a hiatal hernia repair. What else do I need to have checked out?