Have you asked the vet about keeping It moist? From my understanding, wounds need oxygen to heal and drying out is part of that process. This could be an outdated understanding though.
Bacteria thrive in warm, moist environments, if his wound is stabbed over, it will protect him from infectiong.
I didn't read your whole explanation, but did you give antibiotics? Dog bites are the worst for bacterial infections. I hope its not infection.
Praying for your little trooper.