Since you have Gilberrt's disease;bilirubin(so does the jaundice) will go up or down depending on factors like infection,inflammation;stress level among others. I suspect you may have an infection(ie: like having a cold) prior to or during that period where your bilirubin went way up.
If CA19-9 is normal and the Cat scans are clean as what the report you had mentioned above, I don't think you have any problem with regard to cholangiocarcinoma(CCA) at this point.Please remember,I am not a doctor and I could be wrong,I am just,like you, a patient.
But as you know,CCA in the common bile duct or the extra-hepatic ducts (the stricture) require expert or GI specialist who FAMILIAR with this disease to make the call;that is why a 2nd opinion like at UC San Fran is important before you choose to have the Whipple prodedure done.
My suggestion is :
when you do the next ERCP;ask the doctor to order a CEA lab test for you along with CA19-9 in a month or so; and a PET Scan of" the chest,abdomen and pelvis" too .
Get a 2nd opinion before any big surgery like the Whipple .
In that way you will get a complete picture of your health status.
Please know that my personal opinion is not intended nor implied to be a substitute for professional medical advice. If provided, information are for educational purposes.Consult doctor is a MUST for changing of treatment plans.