It is very common for dogs 13 years or so to have degenerative joint disease (arthritis). The parts are just wearing out. The problem can occur anywhere there are joints in the body, which include her spine, hips, knees, ankles, feet, shoulders, elbows, wrists, and even in her tail. Lyme disease can contribute to joint pain and should be checked often and treated if necessary.
Nonsteroidal anti-inflammatories such as Rimadyl or Previcox do help with joint pain and work to decrease inflammation which can further help to deteriorate joints. Other medications such as Tramadol work with NSAIDS to help make them even more effective. Nutraceuticals such as glucosamine (which she is already taking) and Omega 3 Fatty acids also help adjunctively.
Acupuncture either as a solo treatment or as another adjunct is also valuable for arthritis, as are Chinese Herbal Formula's for arthritis and pain.