it could be some type of mange this causes dogs to lose there hair alot take them to a vet right away
I am not sure but if she has nothing visual, definately take her to the vet....have you considered a yeast infection in herr ear canal? Just a long shot but i know some breeds, usually with longer hair are prone to them. Definatel a vet visit though!
My dog has this too and the vet is not sure what it is.