The purpose of this study is to determine if the Pain Relief Patch, which shines light of a limited wavelength on the painful area of the back, relieves chronic musculoskeletal back pain. At the same time, this study will gather information on side effects associated with use of the Pain Relief Patch. The study will compare the Pain Relief Patch to a patch that is similar in appearance, but which shines a different, presumed nontherapeutic, wavelength of light.