It concerns me that you say you think he is dying. I don't want to come off harsh here, but you owe it to this pup to make sure he gets proper care. Perhaps you can speak with the vet about waiting for insurance reimbursement....perhaps you can apply for Care Credit...or do you have friends or family that can help?
You need to think all of your options...and if all else fails, please turn him over to someone who can help him. Either ask a vet if they can take him...or a rescue. I believe that United Yorkie Rescue has MI foster homes.
United Yorkie Rescue - A 501(c)(3) Non-Profit Yorkshire Terrier Rescue Organization is their website.