Loss of appetite is symptom of many disorders like diseases of gastrointestinal tract, kidney, brain, blood, skin, nose, mouth, throat, and eyes. Pain is another cause of loss of appetite in dogs.
There are 2 possibilities in your dog. Either your dog is having any of the above mentioned disorders or he is having pain in the legs area that is why he is unable to walk.
Pain can be due to muscular and skeletal problems, disc injury, traumatic injury, damage and inflammation of the
tissues, exposure to heat and cold, and some diseases.
You should take your dog to vet who may order for x-rays and some lab tests to confirm the diagnosis. Treatment depends upon underlying cause and can be supportive or specific problem related.
My dog has stopped eating and I just noticed that she has diarrhea and keeps shaking what could be wrong with her.
Its frustrating not knowing if your dog is in pain or if something is wrong. I just recently adopted my current dog from a shelter. He was abused and neglected, which I knew. But right as I was walking out the door to bring him home the volunteer I had working with said " oh he also needs some xrays he has some leg problems it looks like. This disturbed me for a few reasons but mainly two. The dog was going to be put down, that's a lot of the reason I initially adopted him, he had been at the shelter for 9 months, 6 months straight, and then adopted for about a month and brought back for 3 more until I got him. 9 months seems like an awfully long time for a dog that might be in pain or at least discomfort every day. I know that shelters are overcrowded and understaffed, and under funded but that just doesn't seem fair to me. I feel as though honestly that is neglectful. I asked them some more questions, like well is he hurting right now? All the time? What could cause this? Is it his hips? They told me that it only seemed to hurt him after a lot of activity, and when he first woke up or got up from staying still. So yea all the time. This also bothered me because I want to help every animal I can, but not one that may need very expensive operations or medications. I understand that accidents happen, and having a dog is expensive. I had wanted one of my own for 8 years, but 5000 dollars right off the bat to get new hips I did not possess. As ranty as this is, placing an animal with some one and not fully disclosing their health is not fair. I knew I couldn't leave him here now, but I was worried. What if they hadn't said anything? He is fine now and regaining his muscle mass but it still gives out sometimes a bit. My dog had lost the majority of the muscle mass in his back legs, but this was a result of being tied up so that he couldn't walk anywhere so from not using the muscles he lost them. Make sure he is getting plenty of exercise, not strenuous, just strengthening daily movement. Sorry short answer, long rant.