I have a German Short-hair pointer that is 12 years old. He has inflammation of the back leg. It is very swollen right at the knee part of his leg. This has happened before on a number of occasions and has always went down. He does not even want to put any weight on it now. His appetite is also down. What do you think this is, I have seen articles on the web for inflammation of joints, do you think these would work. What is a good pain medicine for a dog. Thank you.