Our 7 year old cocker spaniel has become very miserable these last two weeks.He is walking very slowly, painfully, hanging his head and sitting in weird positions.The vet has diagnosed arthritis and given us a nsaid for a week.Given that it appeared to have a sudden onset I'm wondering whether it could be something else.He has no elevated temperature at the moment and is still eating and drinking.The medicine is helping , but he is going into kennels for a month while we are away and I'm very worried about him.Anything I can do or ask?