Flu or bronchitis can last longer than 4 days so you may have a couple of days longer even.
So long as she is feeling better tomorrow - then I wouldn't be too concerned, that's kind of what we looked for. A bit better each day.
Ours never ate food when congested.
All you can do is keep them comfortable, keep up the liquids, keep the pain meds going (as they suggest), and whatever else they suggest (humidifiers, etc.).
Hopefully she's feeling better soon. I would suggest taking her back in to be assessed (in a couple of days if she's no better) - you'll feel better and they can check her out to be sure it hasn't turned into something else - just to be on safe side.
ETA: The main thing to watch for (what to be concerned over) is if she gets worse at this point. Then I would place a call in to the nurse and ask what to do.