Massage or a warm bath. Some people even take their dog to the acupuncturist! It's a good idea to make sure that if your pet is overweight that you help them lose weight. If they have arthritis, they must still remain somewhat active at a minimum or the arthritis can worsen due to inactivity.
As for pills and the like, I would take the dog to the vet. Animals are sensitive to medications and their bodies can sustain damage that they may not recover from if you try to medicate them without seeing a vet.