Hi, I am new to the forum, I joined to learn about Yorkie's as I am thinking of getting one from a rescue to be a pooch partner for my Aussie. As I was perusing the site I saw your post and it reminded me of my Aussie and an injury she had last year. This article helped me a lot and prepared me for the vet visit.
https://www.vetary.com/dog/condition/front-leg-injury There is also a section at the bottom of the page where you can ask a vet a question for free, and get an opinion on what may be going on. Yorkie's have such tiny legs, couldn't a sprain or fracture be possible?