Update: the vet is puzzled. She is thinking it's viral since the Terramycin and the oral antibiotics have not done much at all. The serum she formulated using his own blood is not working, either. She gave my husband an anti-viral paste, but if I had been there, I'd have noticed it's the same thing we've been giving him for weeks, a lysine paste on his food twice each day, just a different flavor. So, I'm not sure this will work unless it's stronger, but he is not eating his food with this one on it for some reason. May have to put it directly into his mouth.
The ulcer on his cornea is very large and the other has a cataract on it (another drop to relieve pressure goes into that eye). I'm afraid he'll end up blind and never be able to go outside again. He's never been a 100% indoor cat, came to us as a wanderer. The vet is consulting a colleague. She's still fighting for him and not socking it to us in the $$ department. They love Finn there.