Sneezing Chick?

[Quella]

My two black sexlinks are two weeks old and one of them are sneezing frequently, estimated every ten minutes or so. Zeal wipes her beak by "rubbing" it whatever floor there is, and scratches her head like a dog. Whenever Zeal stretches her wings and then puts them down again, they sag a bit, but if I pick her up to see what's wrong, she quickly readjusts it. Otherwise they seem perky and healthy. I don't think I should separate them since they always cry out for each other when they're apart, but is it necessary? I've heard that sneezing once in a while is fine, but they sneeze much, much more than that. More than enough for me to notice it often. Should I keep them inside, since I've started them out?
Nothing really has happened really so I don't think it could be trauma, although they just got moved to a larger brooder. Both of them are drinking and eating fine. Poo is normal. I haven't done anything yet, I have just noticed this, the bedding is shredded paper and the "house" is a cardboard box.