Hi,
Keep in mind I'm NOT a Yorkie expert and I don't know nearly the number of things I would like to know.
But...
That being said, have you taken him in to the vet to see if he might have an illness that would be (similar) to a human's Fibromyalgia type of thing?
I know it might sound weird, but it's a possibility. He might have some sort of pain that occurs when his body is touched...causing him to not want to be held or loved on. Some sort of sensory processing disorder maybe?
I think it's at least worth a look into.