Baby chick sneezing, no visible discharge?

[Brisket]

I have a chick that's about 3 weeks old, it sneezes quite often. It is active, eats/drinks/poops like the others, but every time I look at it seems to sneeze. Not frequently enough to be urgent, but suspiciously often. The waterer is very shallow so it would be difficult for it to accidentally breathe in some water or dip its beak to far. I keep them on hay, is it possible it's allergic to the hay? There is also another chick that frequently yawns, however, this one doesn't sneeze like the other. Both are fairly healthy and show no other visible symptoms. I've been watching them frequently and they seem overall fine, but I don't want to ignore possible illness.

 

[oldhenlikesdogs]

Are you changing the bedding often? Hay can sometimes get moldy if it gets wet? Do you have good ventilation?