you need to have a skin scrapping done - one that they allow to grow - not just look at under a microscope immediately.
It may be leather ear - which is a fungus - you can search on here - I've posted about it several times. Here's one of the links, there are others - but there is little info out online anywhere on leather ear or also known as winter ear
http://www.yorkietalk.com/forums/yor...us-yorkie.html
my post is the last one - and it lists what treatment I have used.