Hello and welcome to BYC!

Sorry to hear that your chicken is sick.
Do you know what kind of repertory illness peaches has?
(If so, ignore the following questions. I am just trying to narrow down the possibilities so others on here have a better idea of what peaches is dealing with and how to treat her):
Does she have nasal discharge/raspy breathing?
How does her comb look (any spots/discoloration/scabs present)?
How does her poo look (pictures would be great if you can)?
Have you noticed any blood in her droppings?
How long has peaches been sick (at least that you know of)?
How is her weight (i.e. has she been eating much since she got sick)?
I hope that peaches is better soon! I am not a professional and do not have lots of experience with repertory illnesses but I know that there are lots of people on here that can help.