Biliary pain in an 80 year old patient

This gentleman had a history of biliary pain for the past month. The MRCP suggested the presence of a stone in the distal CBD (A green arrow) and gall bladder calculi (A: red arrow). ERCP showed a diverticulum superior to the papilla (B: green arrow). We kept cannulating the pancreatic duct. Even after a transpancreatic papillotomy, the CBD could not be accessed so we placed one guidewire in the pancreatic duct and went after the CBD again. The technique worked. Contrast injection showed a markedly dilated CBD (C: red arrow) with distal tapering (C: green arrow) without any negative shadows signifying calculi. We did a wide papillotomy and swept the CBD multiple times with a biliary balloon( D1: green arrow showing the inflated balloon at the upper end of CBD &  D2 green arrow showing the inflated balloon at the lower end of CBD) . Clean sweep every time. The negative shadow at the lower end of CBD in the MRCP could have been caused by the diverticulum. This still doesn't completely explain the dilated CBD and distal tapering. Sphincter of Oddi dysfunction is a possibility.