Im not a nurse Im not a doctor am a trauma counselor so with that said perhaps google abx online in use of ducks or poultry and see if there is something that can be purchased without a vets prescription. I live very remotely and the vet for birds or poultry are more than a human seeing a neurologist CRAZY. good luck you sound like a great duck parent and of course pray cause God looks over all creatures. Im new to the duck world but check signs of infection, redness swelling now getting better after 10 to 14 days. That would be my course if I were you. good luck my fellow duck lover. there are those "Ask a vet" online people that seem to be pretty informational and not as expensive as going to the duck vet.