Hello! My chicken, Puffy, has a REALLY bad case of respiratory illness. I know to treat her with Tylan 50. My questions are: 1. Can we use a year-old bottle of Tylan 50 that has an open hole in the top? Did it expire and go bad? Tylan 50 is actually pretty expensive where I live, and that old bottle is the only one I have on hand right now. 2. If I can use that old bottle, I know I have to treat her at least 2 times a day five days in a row. Until I have 5 free days straight that I can treat her, should I treat her only today just to hold her over? I don't have 5 days in a row for a while yet. Thank you so much! Puffy is such a sweet Silkie, and has been with us for a long time; 9 years! I would hate to lose her now.