Any other symptoms?

If it's your youngest, then I would definitely take her to the hospital. 39.6 degrees is a sign of a serious infection of some sort. If it's your eldest, then I might still be inclined to take her to bec checked out, but it depends on whether she has any other symptoms.

Why don't you try Nurse On Call? It's only the cost of a local call, with trained nurses who can do a phone assessment and give you advice.