My dog won't eat, is limping, and throwing up. What should I do?

Thanks for using Petco Pet Education Center, formerly Petcoach! Loss of appetite and vomiting can be observed with many conditions such as gastroenteritis, dietary indiscretion, kidney disease, pancreatitis, among many other possibilities. Lameness can be due to discomfort possibly due to arthritis or something else. This may be related or perhaps may be unrelated and another issue. Lyme disease is a possibility though this is not very common. I recommend that you have Jakey evaluated by your veterinarian for further assessment and treatment. They would be able to check for these possibilities and others depending on the findings on exam. Treatment would be based on findings. Good luck and have a great day! Hoping for a speedy recovery!