What are the symptoms of a dog dying?

My dog is an 11year old golden retreiver and he has arthritis i think because his bones are constantly clicking and he moans when he lies down and struggles to get up. He is constantly falling down he also licks the carpet when he feels sick but he does this every night. I have never had a dog die before so i am very scared especially because of how much i love him.

Take him to the vet. He's in pain. Is he on any medication for his arthritis??

go to the vet and ask for an arthritis medication called Metacam:this will help with the joint pain and clicking.Arthritis is not going to "kill " your dog, but slow him down and may moan or refuse to run, refuse to walk stairs etc.Metacam is on prescription only and used for humans also(arthritis)

Consistent diarrhoea, despite no change in his diet. A "change in his diet" could include a type of treat that you've given him before. If it's not something he eats every day, it's a "change in his diet".Loss of appetite, for no apparent reason. There will be an obvious change. It won't be subtle if you pay close attention. If he usually eats half of the food you give him and abruptly starts eating less than half, that can be counted. Little to no interest in water, even after a long walk. He just won't drink anything, even if he's panting. Or he may drink after a walk and then not drink again until the next walk. Dogs usually drink at least half of their offered water every day.He'll start sleeping a lot more often and probably more deeply. He'll sleep when he usually is up and about. He'll sleep really deeply without dreaming and may be difficult to wake.He will slow down a lot. If he used to get really excited about walks, he will lose interest suddenly. He won't care enough to get up and you might have to force him out the door. Or he may be easy to get out the door but once you just get around the corner, he will start panting immediately and walk very slowly.His body language will change. He may let his head hang and only wag his tail if you pay him special attention, though in the past he would always be looking at you and wag his tail if you said his name.He will be in pain. You should know him well enough to be able to tell. It might not be obvious like a limp. It may be internal pain. You can know by touching his stomach area and applying a gentle pressure. If he seems to be in discomfort, there is probably something wrong inside of him.He will start throwing up and having difficulty keeping any amount of food in his stomach. If it's really bad, he will also throw up blood and be unable to keep water down. This is a very obvious symptom and he should be taken to the vet immediately if he throws up for an extended period of time.He might start hiding or laying in places he avoided in the past. Like behind or beneath furniture. This is him literally just waiting to die. At that point there's generally nothing that can be done for him except to have him put to sleep. Even if he's not suffering, there is such a thing as "old age".

Take the dog to the vet for heavens sake. There is plenty of very effective medication available for arthritis.No one on here can tell you whether your dog is dying. Ask a vet.