Right side abdominal Pain usually after eating

My husband had an apendectomy about a year and a half ago. He now gets severe abdominal pain right where the scar from the incision is. The pain usually comes after eating and is so severe that he often doubles over. It is followed by diarreah(sp) but sometimes by small normal stool... The pain has me worried that there is something wrong in his intestines. I don't know if it related to the apendectomy or not. the pain did not start immediately after.
please, any help would be great!!