Hi there, welcome to BYC!
Sorry you are concerned about respiratory symptoms.
Vet rx will not cure anything and basically makes a cool sensation when breathing... like Vick's vapor rub... *possibly* still relieving, though??
Many respiratory things are viral and not bacterial which means the bodies T cells and such need to fight it off and anti biotics are irrelevant unless you can confirm need or is fighting of a "secondary" infection that may (have) set in easier due to weakened immunity.
quarantine is really mostly pointless as well as all birds have already been exposed. That bring said... I still do it to prevent any more bacterial or viral load shedding among the flock. Like you state, I will even cull and consider it a very effective means of controlling most things. Most antibiotics like Tylan have become not legally available over the counter in the recent past.
Whether you're over reacting or not is hard to say. But over use of antibiotics does NOT benefit anyone and often renders them ineffective when actually needed.
Try not to forget that if your birds are not under an abnormal amount of stress that their own bodies should also be producing antibodies. All things immune system related are impacted by nutrition first, after genetics. Keep nutrition high by using a formulated ration for the species, age, and genders you keep. Be sure nutrients aren't diminished by excess treats like corn, scratch, meal worms, etc... no more than 10% of total daily intake.
How old are these birds now and where did you get them from? Adding your general location to your profile can help peeps make the best suggestions possible at a glance.
I personally would not be treating. I might offer a short term boost in the nutrient department... my favorite is Rooster Booster (brand) Poultry Cell (product). NO supplement (including ACV, which must be raw and unfiltered for the probiotic effect) should be given longer than 10 days in a row. If you don't mind, what are feeding regularly including treats and supplements?
Sometimes a sneeze is just a sneeze... most often seen in my flock during dust bathing. Paying attention to other symptoms or circumstances can help weed out cause for concern verses just good paying attention.. which it sounds like you are.
I do understand that my preference won't be the right answer for everyone. You MUST do what YOU think is right for your flock.
Hope all is well and your flock thrives without illness!
