Debbiezam ... sorry about your baby! Fasteddie is right ... find a vet that KNOWS Yorkies! Our Dr. Lucy is wonderful, we have her on "speed dial" at her office and at home!!
I wouldn't take that baby back to the pet shop ... they probably would not make the effort that you are making to try and help him get better! We too made a large investment in our Toto, but there is a point when the money doesn't matter [for us it was five minutes after we actually had her in our arms!!
] I quit counting after Papa bought her 7th bed!! My rationale is that "Toto just requires lots of stuff"!! She is our joy! I certainly understand how you must feel and you can rest assured that we will keep that baby in our prayers!! Keep us updated.