kidney failure

Hello,
my dog is 3 years old, big size.He was a stray puppy when I found him 3 years ago wandering around in a bad condition. First 2,5 years he was drinking too much water and vomiting quite often after eating his dry food. Vets said that he had sensitive stomach but 6 months ago we were really concerned so we did more medical tests. After he did the ultarsound, it showed that one kidney is destroyed and the other is atrophic. So he was diagnosed with kidney failure, stage 2 ( 3.5-4 creatinine) and he started to eat a specific dry food, Ω3, pill for pressure and saline iv 600 ml every day . Last month, the results worsened (creatinine 5) and the vet told us to reduce the dry food and to give him broccoli, sweet potato, rice, carrots and saline iv 300 ml day after day although after a week cretinine increased to 6 ! Please can u give any advice about this susbject, especially about nutrition? My dog looks so happy, running, swimming without having any negative symptom anymore, how is this possible?
Thank you in advance

Maybe from now it wont see the effect of his infection but one day you notice the changing in your dog that having disease like that! Grilled egg shell has a lot of nutrition that our dog can get mix it with the food that you prepared for him. It's sound's like your dog food before is not fit to your dog. You said it that your dog have a sensitive stomach in short your dog had allergic reaction about the food you gave to him. Mine have the same problem before sensitive stomach and while i'm searching I found out about high quality dog food for dogs with allergies and It helps me with my problem hope it can help you too. About the kidney problem is that a chronic or acute? Always monitor the amount of food and water that you give to your dog everyday to prevent the dehydration, and always monitor his weight every week to see if he improves and gets the enough nutrients and calories and see if he maintaining his weight and proper hydration.

Thank you for your reply. The vets were saying that he had sensitive stomach but actually the problem wasn't neither the food nor the stomach but the kidney failure that we found out the last 6 months. After he started a specific diet he was fine, he didnt vomit. He has chronic renal failure, probably congenital. I still cant get it how he can look so happy without any symptoms and be at the 4th stage (terminal). I am desperate of hope maybe that's why I can't face and accept the truth.