My dog is very sick :(

I feel so drained, so tired today. My dog is very sick. Its 11 years old, it`s old enough to be a grandpa. I have had him with me since i was 11. When he first came he was only 6 weeks old, very small, very curious and playful. My sister named him david, but its a human`s name. So we got him another name, that is vacuum. However he prefers the name david, so he is always david to us. We have had a good 11 years with him. He is smart and very playful. He loves poking his nose around, he loves outings. When he was young, he was very very active, always finding opportunity to sneak out of the house to play. He got lost once but we found him back. He quitely become notorious among my neighbours as he would run ard in the corridor and even sometimes into their houses looking for ppl to play with him. Its quite a sight with my dog running as fast as it could with me and my sister after it trying to stop him by pouncing on him. Years passed, it lost it`s sight due to cataract. However it is still active for its age. Partially blind, he sniffs its way ard the house. Sometimes when it is excited, it runs ard and bangs into furniture with a loud tud!!! With age his taste for food changes as well, no longer does he like beef, he now likes to eat oranges, apples and certain vegetable. It has turned vegetarian...hmmmmm ???
Recently we brought him to stay at the pet hotel, as my mother is going overseas for holiday. When he came back, he was a sorry sight. He is a shadow of his old self, sitting quietly hunched in one corner. When we tried to talk to it, it jus sat there head down, looking at u. It feels so heartbreaking. His face is lumpy and he has lumps on his legs as well. He walks in a very painful manner, inch by inch, all the while with his head hanging low. We brought it to the vet. They did an x-ray and a blood test on it. They said that they will tell us the results the next day. When he came back he seemed to be slightly better. However it still doesn`t eat or drink. He still looks to be in pain, but its happy to be home again. He must have been really homesick when he was staying at the pet hotel. His eyes have a lot of dried deposits around, so i guess it must have been crying alot. I really hope that his will be fine. Dogs can live up till 15 years, some even up to 18. Please, please don`t let it leave us so soon.......