i have a 4 week chicken that is breathing hard and fluffed up. when i picked it up fluid came out of its beak. it is eating but its craw didnt seem very full to me. i have tylan but its so little ! i gave injections to my larger birds about a month ago. these babies have not been around the others and i always take care of the babies first. also the symptoms are not the same. can anyone advise please?