If she is not wheezing or sneezing throughout the day, it may be that there something causing a bit of an allergy on the coop. - bedding may be. If you notice the symptoms continually then it could be a respiratory infection. There are lots of threads on such problems for you to search.
Personally I would leave her with the flock as its more than likely that the rest of the flock will have contracted the disease (if indeed that is what it turns out to be) and give vitamin supplements or electrolytes in their drinking water as this helps boosts their immune system. In the meantime, read up on respiratory illness here on BYC and monitor your sneezer.
Al the best
Ct