Usually, by the time you notice someone has the CP, everyone's already been exposed. There is nothing you can do at this point.
The vaccine does not guarantee immunity...and the immunity it does give is short-lived. If she does have the CP, she'll have lifelong immunity. Not every case of the CP is a bad case. My daughter is not vaccinated and when she was exposed to the CP, she had no symptoms except for a fever for 3 days. I didn't think much of it and when she hadn't "gotten" the pox by the time she was 5 (this past year) I had her titers checked and she's got full immunity.
You can always take a picture of the pox and email them to your doctor (most won't want you to take your daughter to the office) and see what they say.
Also, as another person stated, it could be impetigo (http://www.nlm.nih.gov/medlineplus/impetigo.html). Chicken pox USUALLY (but not always) starts on the abdomen and spreads from there. Impetigo can start on the arms, face, and legs.