Nurses know, too; they just can't tell you because they are not licensed to give medical advice.

Once, in a situation when we really wanted an opinion from a nurse who wouldn't give one, we finally asked, "If it was your daughter, what would you do?" With no hesitation, she told us exactly what she would do. She just couldn't tell us what we should do.

That phrasing has proven to be useful a time or two since then...