My babies are sick. I introduced four new chickens last weekend without knowing to quarantine them (duh) an they were sick. Now my original eight are sick too. Sneezing, coughing, gurgling, runny noses. My vet friend recommended medicated chick feed with tetracycline. Well I can't find any but I did find a water soluble powder version. I just can't figure out how much to use for a gallon of water. The directions are confusing. I just want my chickens to be healthy again. Any suggestions??