Arianna has pneumonia

We took her in last Thursday and the pediatrician said she has pneumonia in the left lower lobe. We started her on Cefdinir and she seems to be doing well. Hardly any need for oxygen. But she is staying home from school and activities. It's Tuesday and Im a little concerned that her sats are not staying where I would like. They were great yesterday so Im not sure whats going on. I'll take her for a follow-up with the pediatrician on Thursday.