The duramycin is an antibiotic and will do nothing for your chick if she has cocci. This is a good reminder for anyone who is raising chicks to always have a cocci treatment on hand - I keep both sulmet and corid stocked up at my house. Unfortunately, I've found that employees at the farm stores know little to nothing about raising chickens, but are not shy about offering bad advice. Chicks that are as sick as yours do not usually make it, but you can try giving her some vitamin/electrolyte water via syringe (I use the poly-vi-sol mixed in pedialyte or even sugar water) and if the chick seems hungry, I mash up a boiled egg yolk and mix the med water with it to a runny consistency and feed that with syringe or eyedropper.