We have a 1 1/2 year old rooster and a hen who are acting differently than the rest of the flock. They are sitting in one spot all days long, their feathers are rustled up around their necks. The rooster has quit crowing and they are lathargic. The appear to be sick and I am worried they have some kind of sickness. We have separated them from the rest of the flock. We need to know if any of you have had chickens sick like this and what did you do to treat them. Is there any kind of anti botic I can buy at the feed store to treat them ourselves? A prompt answer would be appreciated.