This is likely pyoderma, which is a common skin infection - secondary to environmental allergies. You *need* to take your kiddo to a vet ASAP as the only way to get rid of pyoderma is with a prescription antibiotic. The vet will need to do a simple, cheap skin scraping and look at under the microscrope to confirm it's pyoderma (staph intermedius).
From there, you need to figure out if the allergies are year round or seasonal. If year round - then you'd want to treat w/ either Apoquel or Atopica or Cytopoint.
Read this entire thread about allergies:
http://www.yorkietalk.com/forums/die...tart-here.html