Azithromycin?

I know Azithromycin continues to work even after its finished but does anything know how long it continues to work? My daughter was diagnosed with a sinus infection this past Sunday. And was given Azithromycin and Prednisolone. She took her last dose of the Azithromycin last night the 30th. And she's still got a stuffed nose with mucus and also still has the cough that also is mucusy, or sounds that way. She's had this mess a total of a little over a week. So I'm wondering if I should give it a couple more days or take her back to the doctor?