Have you ever seen any sneezing or respiratory diseases in any chickens or poultry you have ever had? Is the chick lethargic, having gasping or sneezing? Respiratory diseases can show up around 3 weeks old if chicks have been exposed by a carrier. If you think it is a peck wound, it should go down. You can buy Terramycin eye ointment at most feed stores, and it is applied into the eye twice a day. If it is a respiratory disease, I would use the Tylan, and give it orally. It does have to be withdrawn from the vial with a syringe and 20 gauge needle, then remove the needle to give it orally.