JC, as in humans, the foreign protein in a vaccine can cause a local immunological response as in a painful tender area, and frequently a mild fever. If she was fighting during the injection, there could be a small amount of trauma in the muscle. Being a kitten, it usually only last about a day.
Thanks for the info... She is acting ok, but she certainly is not out going.... I am tempted to feed her and put her to bed early... That may help her some.