Ahhh...honey...you can not let this go untreated. As others have stated this would be considered neglect/abuse.
If you can not possibly afford his vet care, Please contact a Yorkie Rescue in your area, and you may have to surrender him, as they would be able to raise the funds needed to care for his injuries.
http://www.yorkietalk.com/forums/yor...ie-rescue.html