Have you got panadol hun, if not i can run a bottle over, it's safe to alternate b/w nurofen & panadol and then you could give her the nurofen again at the 6hr mark.

If your worried then i'd take her to hosp and get her checked, it's sooo not like her to be that lethargic even when sick right?
Theres no harm in getting her checked, if you need some panadol i can race it over so you don't need to wait for DH to finish work etc.