Our otherwise healthy male boxer 5 years old has displayed very strange symptoms for about a week, which started suddenly about a week ago. He suddenly became extremely anxiety-ridden -- running from room to room, not resting, jumping at the slightest noise, and panting a lot. He suddenly has separation anxiety also. He had an episode of shivering last week which lasted about 10 minutes and then stopped. He's had kind of intermittent appetite and some occasional diarrhea, but not bad. He's drinking more water then normal, but his tongue seems more red than its usual pink. He's definitely not lethargic, and he's not losing weight, and his coat is still nice and shiney. Nothing has changed in his diet, surroundings, etc. I've googled these symptoms and all I get is anxiety disorder. Some of them show up under other diseases, but then he doesn't have the main symptoms of them. We will be taking him to the vet. Does anyone have any ideas?