I have 15 chicks that are almost three weeks old, and this is my first time with chicks. This morning I heard a tiny little noise that I thought could be a sneeze but I didn't see where it came from. Just now I went back out to see them and I found the one that is making the noise. I THINK it is sneezing but I have no real idea... it sounds like tiny little puffs of air now and again and he/she moves his head a little when he does it. He/she seems totally well otherwise and doesn't have a runny nose or anything and is running around eating, playing, etc. Should I be concerned and if so, what should I do?