My Husband Has Had Recurring Pain In His Right Kidney

My husband has had recurring pain in his right kidney area for the last three years. The pain comes on suddenly and can hurt for a few hours to a few days. No kidney stones and kidney looks healthy when scoped to retrieve what they thought to be a 3mm stone that ended up being absorbed by the kidney. This pain is the same felling he gets when he gets stones but now his Dr is saying it's probably not due to his kidney. Any ideas where to look now?