My female geman spitz is not well,wghat to do??

I have a German spitz female of 5 years old. She had delivered 4 pubs at the age of around 3 years. Of late suddenly she has lot of pain in her legs and shirks whenever we touch her legs. The pain appears to be more on the back side right leg because of which she is now fearing to stand even. apparently there was no earlier illness which she got. very recently about 10 days back ( 18.06.14 to 28.06.14 period. Checked with one local vet as no qualified vets are around. her feet keeps trembling and she is sleeping or lying down more than normal these days with very less appetite. her boy weight is about 13 kgs and height of a medium sized dog about 20 inches. Kindly suggest what could be the complication it is not Parvo as only the feet is trembling mainly with pain I suppose.