Dog acting unusual

Question
My fiance and I have 9 year old German Shepard Mix that has been acting strangely the last few days.  She has been noticiably less active and shivering.  There are no apparant injuries and no tender places on her body  to the touch.  She is eating, drinking, and relieving herself normally.  This evening it got to the point that she shys away from us and our other dogs (they get along well) and will not even jump onto the bed or show any other enthusiasm.  Any suggestions would be helpful...  

Answer
You need to take her to the vet for an exam.  I would have her tested for Lyme Disease as it can cause sore joints, flu-like symptoms and fever.  Otherwiseif that is negative, I would recommend other testing such as a CBC and Chem screen to get to the bottom of it.