My german sheperd has started trembling, acting restless, going on my couches (which he never does), loose stools and won't eat or drink during these episodes. He has been tested for heartworm and a battery of tests show nothing wrong. Sometimes the wierd behavior lasts for asouple of hours to all day. The vet suggested he might be havung seizures but I don't thinkso because he repomds to my commands ( sit, give me your paw). When the episode passes he is fine and playing and eating normally. Can any one offer any suggestions?