Hello,
I have had a few dogs throughout the years that this has happened to. They getting a fight and avulse (pull the tooth out of the socket) the tooth in the process. For these cases I always do a dental and remove the tooth (it will not heal) and then close the gums after removing the broken bone around the tooth root. Your dog is essentially going to lose that tooth but with the dental surgery you can close the area so that they don’t have pain or get infections. Please see your vet asap and talk to them about this. Until then I would feed soft food and avoid playing with toys.
I’ve heard of it and have friends with a cat who needed a nebulizer treatment daily.
If you can afford a second opinion, by all means, but it’s not unheard-of.