my dog is acting lethargic, he has been eating normal and going to the bathroom, but seems to be strained on his hind legs. he will sit on his legs but will not lay dowm. he seems shaky and sad. someitmes when u go to touch him he yelps, almost scared. he has been traveling to a couple of houses for the holidays. could it be that he is overly excited or anxious or could ha have gottem sick at someones house. i recently broke up with my longtime boyfriend that he(the dog)was living with, but now he is living with me. please help.