Some of my 8 chickens have started having a little clear discharge from their noses. The inside of their noses also look inflamed. Some sneeze, but not often, maybe 1 time in an hour. Two of them shake their heads. One seems to be a little puffy above her eyes, which definitely concerns me. All seem to be eating, drinking and pooping normally. All are active. They're between 20-24 weeks old. They were on Purina Grower feed but I just switched them to layer feed since they just started laying this week. Its been really cold here all of a sudden, with the temperature dropping sharply about 20 degrees over the last few days. I also have let them out in their tractor to scratch around for a few hours every day except the days when it rained and a couple days after it rained. So far, I've given them one dose of VetRx in their water. Doesnt look like its helped so far but I'm going to dose them again today since that's all I think I have on hand to help with this. I'm willing to take them to a vet if necessary. My birds seem to be constantly fighting something off, ever since I brought the three new ones in. (I quarantined them but it sure hasn't seemed to make a differeence. I'll never bring started pullets into my flock again.) I've been doing some researching on this site and it sounds like it could be one of several thigns. I just have no idea which and what to do now. Really hoping someone's online who can help me.