I've got a couple of questions for you. When the ERCP was done, was it done with manometry? Was the sphincter cut (sphincterotomy) during the ERCP?
Just as a general note, if they couldn't enter the duct, it would suggest that your sphincter of Oddi pressures were high (but that can only be verified via manometry - which could be important). However, if those pressures are high, you could be experiencing SOD (sphincter of Oddi dysfunction), which is a condition that can show up in some after the GB is removed. It's thought that SOD is 'uncovered' when what was 'thought' to be the source of the pain (the GB) is removed. In your case, they may have found the source of the pain 'early on.'
SOD (again, determined via manometry) is approached by the non-use of narcotic-based meds. Those meds increase the ductal pressures and can make things worse. Yes, the narcotics can dull the CNS so that the pain is perceived less, but it does not help. Specific calcium channel blockers can be uses, and there are also some anti-spasm meds that can be tried. If it is SOD, the typical approach is to cut the sphincter (but ONLY if the pressures are high) and to stent the duct/sphincter to hopefully reduce the chance of pancreatitis.
It's possible that the dilation of your ducts could be due to previous spasms of the duct/sphincter and the 'backup' of bile/pancreatic fluids into the ducts.
When you had the attack, did they measure your liver enzyme and pancreatic enzyme levels? If not, why not?
Whether or not the HIDA scan comes back 'normal,' which I doubt will happen, you should be working with someone experienced with SOD and the biliary system. IMO the GI doc you're working with now/or the surgeon (or both?) leave a lot to be desired as far as their diagnostic capabilities go.