My grandson has pneumonia now but was diagnosed with bronchitis a month ago and was prescribed Augmentin?

Now a month later, my daughter took him back to the ER, where he had a chest x-ray this time and now he has pneumonia. Again, he was prescribed Augmentin, obviously the wrong medicine because it didn't work the first time for the bronchitis. My understanding is that he had been swabbed for the regular flu but not for the H1N1. Does anyone know which medication he should have been prescribed? I tend to lean toward a Z-PAK since I have had excellent experience with it myself in the past for bronchitis, but this is pneumonia. Does anyone know what effective medicines there are for pneumonia so I can give my daughter some information to convince the doctor to prescribe her son?