Sneezing and nasal discharge
Welcome to BYC!
Generally speaking the "medicated feed" that is available is not going to do a thing for respiratory issues as they are designed to control coccidiosis, which is an entirely different issue.....it sounds like you have had the misfortune of obtaining stock from a breeder who is either ignorant or uninterested in helping you, neither of which is good.
Is the discharge thick or thing and watery? Is there any swelling around the face/eyes? What are you bedding the chicks with?