Poorly German Shepherd

Question
My 8 yr old GS, male is not very well. It started 7 days ago, he had diarrhoea and vomiting. I thought it had got better after a couple of days, but it seemed to get worse. He will hardly eat anything and wont drink any water. He went to the vet before the weekend and he was giving medicine. We took a urine sample back to the vet today and it now turns out that he has something wrong with his kidneys. He is due a x-ray tomorrow first thing. I am worried as his brother (they were bought from the same litter) died 2 yrs ago. He had a lump which turned out to be cancer and never returned from his visit to the vet. I am so petrified the same is going to happen. He is usually such a kind hearted, warm dog who wants to play at every opportunity (he acts more like a puppy than an adult dog!) but now he is not interested in anyone or anything. His eyes have lost their spark and he has developed a really bad smell. Do you think it could be more serious than just an infection?

Answer
It is really hard to say.  We had a huge tumor removed from our lab at 12 years old, and she had another 3 good years.  All I can do is say work with the vet.  Sometimes kidney problems can be eased by diet.  Your vet will know if so in his case and the best diet.