What would cause bilirubin to jump from 0.3 to 1.0 in ten days?

Lots of things: These are both nice normal values and often this goes unexplained. I once shot my bilirubin way up just by slipping while running and getting an impressive backside bruise -- it got the blood donor center all bothered and i had to tell all. Best wishes.

Bilirubin: 1.0 bilirubin is not abnormal according to us standards. It varies and there is a chance of it being low next time you check it. Also, are referring to the same fraction of bilirubin? There is total, conjugated and unconjugated. Make sure the # refers to the same fraction.