K.V.
I would opt to take her to a naturopathic(sp?) doctor. There could be a definite connection between the vaccination and this allergic reaction....especially if it came up sudden shortly after the vaccine.
You can find a naturopathic doctor in your area from here:
http://www.naturopathic.org/findannd.php
Allergies do appear at joints(such as knees, elbows). Definitely go with your "gut" feeling.