thanks Herne,I took him to Veterinary Surgery today,when he saw my dog he wanted to sedate him because of his size, but i told him no "killer" is very well behaved.he said it's the biggest dog he has ever seen and his assistant was rather scared of the dog not being sedated which i thought was a little strange, and then the name "killer" didn't help their nervous that much haha. but all in all it went well, they did a couple of tests and found nothing wrong I just have to put vitamins in the water and they think he's simply homesick.