Suggest Treatment For Abdominal Pain Post Colonoscopy

My 73 y.o. husband has had lower abdominal/pelvic pain for over a year. He has seen a gastroenterologist who cleared him after a colonoscopy and MRI. He said all he saw was diverticulosis. He has also seen a urologist who did a CAT scan and cystoscope of his bladder. He did not see any signs of cancer. However, he did have prostate cancer in 2002 and was treated with radiation and the implant of radioactive seeds. Since then, his PSA has remained very low. He has had no constipation, diarrhea or nausea and has no fever. He has occasional blood in his urine and occasional night sweats. He is of normal weight, eats a healthy diet, and exercises daily. But the abdominal spasms persist and he feels bad after each one. They occur daily but thankfully, do not last all day. And they do not occur while he is sleeping/lying down. Do you have any suggestions of who we should see next or what we should do? Thank you.