PetSmart gave my puppy Mange?

 

This is my puppy Toot.  As you can see, she looks very health.  She's about 10 weeks old pitbull.  And she just came from Petsmart in Macon Georgia.  We don't have another dog.  But just days later, she started scratching and bitting her self like crazy.  Then few more days later started to notice that she's loosing her hair on her face.  A Week has gone and she looks like an old dog.  Wouldn't eat her food and became very picky with her food.  We don't bring her around with other dogs.  So there's no way she could have caught mange from another dog.  But then I remembered that we took her to Petsmart and ever since then we started having this problem.  

DON'T BRING YOUR DOG TO PETSMART FOR GROOMING!!!  I don't think they sanitize their facility after each dog.  Its the only place I know she could have contact with another dog who have mange.