I agree that you should seperate her. ACV wont treat nor cure a respiratory problem. Inspect her for lice/mites. Give her tylan injectable 1/2ml injected into the breast muscle just under the skin once a day for 3 days. Alternate breast and injection sites each day. Then give her scrambled egg with buttermilk mixed in feed for the next 5-7 days.
I agree with you for the most part. but I have had huge success with acv as a preventative treatment, and when used at the first sign of "bubbly eye". it could just be the differences in our areas. as I said before though, if you don't see a sign of improvement in a couple of days, start antibiotics. where we might differ is the acv is way better if its raw. I haven't had a lot of luck with pasturized, but I will give it in a pinch if im out of raw and its midnight.
here is a link that I found that might shed some light on the subject.
http://www.grit.com/fresh-eggs-daily/the-holistic-trinity-apple-cider-vinegar-garlic-de.aspx
when I am unsure of a problem, if the chicken is eating/drinking and the weight is good; I always start with the mildest treatment I can. then work my way up. now if the chicken has lost weight, gasping for air, or appears in very bad shape, I will start the tylan immediately.
I use tylan 200 with 1/4 cc injected into the breast on standard fowl. on my bantams I use tylan 50 at .5 cc administered the same way. cc's and ml's are the same thing so if your syringe is marked with ml's its the same direction. as far as needle I prefer 1/2 inch 22 or 24 gauge. when you give the shot; push the needle in then pull it back just a little and look for blood, if you see blood, move locations and try again.
I do believe dawg knows what he is talking about, I have seen several posts of his and realize he knows his stuff. but he is in a lot warmer climate than we are. here in ohio or temperatures this week will range from about 32 f to 85 f. molts this time of year can cause colds in our birds. the cold's symptoms will be (typically) slight rattle in breathing, bubbly eye. with no swelling around the eyes wattles or comb. if you see swelling then its time to reach for the tylan.
the buttermilk and scrambled egg is a great treatment after any problems were medicine has been given. I use yogurt, but buttermilk is probably easier to find. the scrambled egg adds a great source of digestable protein without causing a huge weight gain and fatty deposits by the vent. most "sour" dairy products contain a great probiotic for chickens and promotes digestive health.
best of luck,
brian