hi the tylan50 will help with that too.as for the breast remember I said first pull back on the plunger and if blood appears then reposition you know your fine and good to go when the blood does not appear.its about 3 inches away from the keel. as for tylan50 most ALL feed stores carry it.its in the section for cattle usually. remember I said the bottle will say for cattle and swine. but not to woo worry. .many poultry owners use it including myself. yes its likely the symptoms will worsen until your able to get the injection.may I suggest you watch a YouTube video that has a tutorial on how to give a breast injection. just look up injecting chickens with tylan. the video should come up.or search online for injecting chickens in breast.it might help give you the confidence you need. usually chickens won't even flinch with the injections. you will see. you likely will need to make a trip to the feed lot yourself for the Tylan. I've never seen a feed store NOT carry it. its extremely common. I wish you the very best of luck. give the antibiotic time to work. not much beats tylan for respiratory illness so your doing the best you can do for her. just know you should see improvements in a few days. best wishes to you. you CAN do this. your in my thoughts and prayers. best of luck.