Well after a lot of digging I found out that Mimi has been in the doggie system here. There were some people that had a lot of little dogs that were used as bait dogs. Well Denver animal control had put Mimi back together after his neck was torn apart by other dogs. They are not sure if he was put in a shelter or adopted offline, or just given away but.
That explains the lumps and scars that you can feel in his face and neck, the lack of teeth. I spoke with the vet that repaired him and they said his lip was tore halfway off. He said that they had to take out most of his teeth to fix damage and that his teeth were not in place correctly to begin with.
This all happened about a year ago.
Poor little guy has been through so much! Thank god he got out of that house and somehow found us.