Fever for over 5 days, cough and congestion

I have a 5 year old daugter that started with sore throat and low fever 5 days ago. We brought her to the Pediatrician after the 3rd day of fever and the pediatrician did not see signs of Strepthroat, a fast culture was done and was negative.
On the fourth day of fever we brought her to another Pediatrician a he formulated an antibiotic (azithromyacin) as the Dr suspected it was an upper respiratory (bacterial) infection. Its been almost two days since my daughter started taking the antibiotic and we have not seen signs that the fever is down. The fever is at 100F and she is still coughing (but not severely). She breathes ok and she is still playful even with the fever.

Is this some type of viral infection that lasts over 5 days or do we need to give more time for the antibiotic to work.