Is Maggie having bloody diarrhea? If so please go to this page and see if this sounds similar to what is happening to her.
http://yorkieviews.com/hge.htm HGE has been misdiagnosed many times in toy dogs and they end up dying because the vet did not treat for the right thing. Don't know if this is what is happening to your little one, but it is worth the effort to ask your vet if this could be what is wrong with her.