Gallbladder pain, ideally speaking, should not be in the epigastrium but more to the right. Stomach pains are epigastric and in your case the investigations of the stomach have been normal. This would leave two organs that lie behind the stomach that need to be investigated, that is the pancreas and the transverse colon. Pancreatic pain can affect after meals and frequently related to the gall bladder. I note the HIDA scan showed incomplete gall bladder emptying. To obtain more information I would suggest ERCP which will not only outline both the pancreatic and biliary duct systems but also will outline the gallbladder and the possibility of minute gallstones in the duct system, which would support removal of th organ. Liver function tests and serum amylase would further aid to the diagnosis of gall bladder disease and pancreatic inflammation as causes for the pain. Finally, the transverse colon pain. This can be due to spasm, as a manifestation of irritable bowel syndrome and it is not uncommon to get epigastric pain after meals. If all these investigations become normal and after exclusion I suggest a trial period of antispasmodic drugs, if they help. Your gallbladder still functions 25% which, though low is perhaps adequate. If however the drugs do not help one has to act on the available evidence and only then I would go for the removal of your gallbladder.