What Causes Abdominal Pain With History Of Gallbladder And Appendix Surgery?

My husband has abdominal pain, in the area where they removed his gallbladder and appendix..(2 years ago.) .It radiates to his back occasionally. Not a lot of gastic activity- belching...and he is regular in his morning routine and nothing changed in that respect. He has taken Prilosec for the week to see if that would ease the discomfort....it does help temporarily......but then the discomfort returns. No particular food or drink triggers this pain...... Any suggestions??