It can all vary depending upon the patient and their pain threshhold, but cholangio is actually one of the more painful cancers out there. I had a long discussion with some doctors and nurses at MD Anderson in Houston, and the bottom line is that it's painful and often warrants very strong pain medication. I concur with Jeff's suggestions 100% - I would get your sister into see a doctor and see what they can do for pain management, assuming your sister is experiencing pain. Additionally, regarding her dizziness, I would have the doctor evaluate that further. It could be something associated with the pain, as Jeff suggests. But it could also be something else.
Is your sister being treated by a cholangio specialist, or a local oncologist?