I'd take her to the vet and check for:
1. Vaginal infection
Get a blood count and see where the rbc 's wbc' s and plasma levels are. Given those results, I'd spend the money on a babesia or Elrichia test. Anytime a dog doesn't eat, it's a concern, I'd give some vitamin B right away to to see if it gives some appetite, but I'd take to the vet right away.