I just got four chicks - at one week old. Now at two weeks the one chick seems to be sneezing. It has no other symptoms and no runny eyes, no discharge nothing. The flock that they hatched out of is also healthy seeming, but i know sick birds can be carriers. Do I cull this chick to save the flock? Do I have to get rid of all four? I have them quarantined form my main flock.