I would look for another vet and take your baby right away.
Yes it could be allergies, or it could be a bug bite, but it could also be many other things and neither one of them should be treated as "oh she is just fine go home" specially if she has now stop eating.
Dogs don't need to talk, their life is their message ~ unknown.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated." ~ Mahatma Gandhi