She probably needs an antibiotic and my go-to is usually Baytril but I am not sure you can get that at a feed store I have always had to order online. The Vet RX may help her breathe better it works similar to vicks vapo rub for humans.
I'm not even sure you can buy meds at feed stores any longer might want to call and find out what they carry. Vet RX might help some with breathing. Sounds like she is pretty sick. Hows her poop looking?