This may sound off the wall to you... but had it not happened to me I wouldn't suggest it. I would have bile acid testing done. My Teddy Bear had a liver shunt that went undiagnosed until he was an adult. I do blood work on all of my pups at least yearly and more often if they are ill....Teddy never had ANY alterations in his blood work, so if anyone tells you that they show up in the liver enzymes first, that simply isn't always true. There were two symptoms that were missed...he took some time to recover from anesthesia and pain meds after ortho surgery .. and he had occasional vomiting over the years. Honestly, this may not be what is going on but it is a cheap test and good to rule out a shunt. The other thing that comes to mind is IBD... Teddy does have IBD as well but many shunt pups do. He is on Hill's Ultra ZD
IBD is pretty common in yorkies...I talk with yorkie owners often whose pups have IBD.
Teddy's shunt surgery was done in 2013. Here is the thread about that:
http://www.yorkietalk.com/forums/sic...ver-shunt.html
Hope you get an answer to this....you might want to consider seeing an internal med specialist.