Terramycin may not be available or found in some stores, but generally you can order it online through supply houses without a prescription. Some states may be restricted, but it's worth a shot seeing if you can order it. Try Jedds. And while you are at it, I would get some Tylosin as well if you want to see if he will make it.
https://www.jedds.com/shop/terramycin-ophthalmic-ointment-18-ozpfizer-a-h/
As for finding a vet, you will need to do a local search and call around to see if any treat poultry. A lot of vets, while very good with other animals may not be familiar with poultry. You may want to check out the link below and see if any of these are in your area as well.
http://www.poultrydvm.com/poultry-vets.php
In the meantime, I would continue to clean out the eyes 2-3 times a day and use original Neosporin in the eyes to help give him a bit of relief. Does he have a lot of mucous or plaques inside the beak too?