I have a 9 month old barred rock who has been having diarrhea (yellowish white). She also has had a droopy tail and a pale floppy comb. We checked with the farm store where we got the chicks and the "chicken guru" thought it was some sort of bacterial bug in her GI track. He recommended we treat her with Sulmet (sulfamethazine sodium) for one week. We did this and she showing no signs of improvement. Any ideas of what else it could be? I don't want the rest of the flock to get sick.