Hi, my question for you is, what were the symptoms when the infection first began and what symptoms besides fever is she having now?
Any rash on the face or ear?
There is a condition called Ramsy-Hunt syndrome which is Bell's Palsy cause by Zoster virus (shingles virus).
Other considerations include Epstein Barr Virus and Cytomegalovirus (both causes of long-lasting viral syndromes).
To answer your question...if it is a viral infection fever can last up to 2 weeks; often times there is a superimposed bacterial infection that causes the fever to persist.
I am concerned that her fever and Bells Palsy may represent something more. Antibiotics are prescribed for bacterial infection, not viral infections.
I would recommend she have a CBC and a chest xray, to begin. She certainly should see the doctor again or perhaps another one for a fresh opinion.