I'm suffering from a severe sinus infection and a throat on fire right now so I'm very irritable. I've stopped myself from posting several times because I know I am, but I just have to say something here. Even if I wasn't irritable, I'd post this but it might come off harsher this time than on a normal day. I apologize if it does.
I do understand going thru hard times and losing your job and being without a home. Trust me - been there, done that. Won't get into the details but I absolutely know the downward spiral it feels like and the depression that can come with it and all of that.
However, with that said, you were told 4 years ago that he needed a dental. You mean between 4 years ago and last year when you got a new puppy (who's since been spayed, microchipped, and had 2 baby teeth pulled), you couldn't have taken this particular pup to get a dental?
Just a question I needed to ask out loud. For now, this baby is in obvious pain if he won't let you brush his teeth and is bleeding. Almost certainly has an infection. If you can't afford the dental right now, please at least get him in to get some antibiotics and something for pain. If you can't afford and can't use care credit, perhaps you have something you could pawn or sell or some friends or family that could help?
Just doing a regular vet visit and getting these meds will be a lot less than $300 so hopefully you can do that now and then save for the dental. While at the vet, ask for a new update on price/if he thinks teeth will need to be pulled (they almost certainly will..and that will raise the price per tooth - or at least it does with my vet).
I know you feel bad. I am not trying to make you feel worse. Obviously the vet didn't make it clear how important and vital the dental is back then. Anyway, it's discussed on YT every day almost. I just hope this helps you to realize how much info is here for you and let the info prepare you and arm you with knowledge so future issues don't catch you off guard
Praying for your little one.