Insulinoma ITSELF is a cause of diarrhea (in which case it often looks
like unset butterscotch pudding --sorry but that is the most accurate
description and it would have to be my favorite pudding, wouldn't it?).
 
Check her blood glucose level.  If it is still low that could be the
cause -- low enough to cause runs but not low enough for more marked
symptoms.  I can't off-hand recall loose stools as a possible negative
side effect for either but your vet could look them up, or you could
ask your pharmacy to let you read side effects in their texts if you
don't have refs.
[Posted in FML issue 4430]