I believe I am dealing with chronic respiratory disease in my flock. A month ago one of our hens was wheezing and sneezing a lot. At the time, all I did was mix Grapefruit seed extract in her water which seemed to have cleared whatever it was at that moment. However, she still occasionally sneezes more than usual. Then, a week and a half ago our rooster was having greenish diarrhea and was lethargic, not eating but drinking. After I gave him probiotics in his water he snapped out of it. Yet now, as of a couple days ago, I noticed the same rooster started having trouble crowing and when he runs or is picked up he wheezes. I have been seeing lots of light greenish watery droppings from many of the chickens. Today, I now have a hen who has bubbles in one of her eyes. I went to our local feed store to see if they had any Tylan 50, as I've read it can be given to help treat CRD. All they had was a packet of oxytetracycline hcl soluble powder. Could someone give me some advice as to what I should use to treat them with? I can overnight the Tylan 50 from amazon.com, but if the oxytetracycline should work, I'd like to give them that today instead. I haven't used either product before and would love opinions. Thanks!