Well my dog is a Poodle X Chihuahua and has been like this for a day or so it started happining after being treated for fleas. Now he walks a bit funny either with his tail to the left or the right. And he is sometimes nibbling his bottom. We think it might be either blocked anus gland maybe worms we are not quite sure?! We are kind of worrying about him because we've never had a problem like this before!!!! And comment we will be thank full for!!!