It could be due to removing her from her mother and litter too soon. Even so, as the others said, she needs to see a vet. Take any medical records you may have. You might read through the sticky starting at
http://www.askmehelpdesk.com/dogs/in...tml#post251809
Not eating isn't near the problem of what ever is causing it may be. Most puppies come from the breeder too fat, a great danger to Dachshunds and their backs. Missing a few meals won't hurt. Once the vet gives her the OK, you need to pick a chow and stick with it. Don't give her ordinary milk. It contains lactose which puppies can't digest.