What Causes Lower Abdominal Pain And Nausea While Suffering From Kidney Stones?

My husband has had kidney stone removal attempts for the past three years. He now does not need more kidney surgery. He did get some percocets for the pain. For the last year he has been getting episodes of severe lower abdominal pain causing nausea and vomitting. These episodes are bad enough to send him home from a job he loves and to get him to take a few percocets per episode. He ends up in bed in extreme pain but with no increased or painful urination. His kidney doctor says this is bladder irritation and to avoid certain foods but there doesn t seem to be a pattern to the kinds of foods. The episodes are getting more frequent, maybe now every three weeks. He says there is nothing wrong with him. Your opinion?