It sounds like you've given these birds a load of different drugs, including partial courses of treatment(?), without knowing what the problem even is or whether it's bacterial, fungal etc. I wouldn't be surprised if that was what's caused at least some of the issues you think you're seeing.
Not giving a full course of antibiotics also increases the risk of antibiotic resistance - something that's already such a problem with Enrofloxacin that it's banned for use in poultry in a lot of places.
You haven't answered the question about where you live (country/state is fine, no need to be too precise) and it isn't on your profile. Even if you can't access veterinary treatment, people might be able to suggest somewhere that you could send off fecal samples for testing to see what the problem actually is.