My 2 year old has a fever with a clear runny nose. what could be causing her fever & should i get her checked out?

Likely a cold.: Add in a little cough, a little fussiness... And you've got a cold. No need for antibiotics. Try some tylenol (acetaminophen) or ibuprofen, keep them inside, allow for lots of sleep and rest. If no improvement in 2-3 days and still with fever, you can get them checked out by their doctor. Sooner if they're looking much sicker. Good luck!