PENFS (percutaneous electrical nerve field stimulation) is an FDA-cleared acupuncture-like therapy applied to the external ear targeting several cranial nerve branches including the auricular branch of the vagus nerve to improve pain, physical function, and reduce symptoms of opioid withdrawal. PENFS has been previously shown to provide improvements in fibromyalgia, a difficult to treat chronic pain syndrome, which correlate with changes observed using a special kind of MRI called resting state functional connectivity MRI (rs-fcMRI) that evaluates brain activity at rest. The goals of this study are to rigorously test the initial promising results of PENFS in a much larger group of Veterans suffering from fibromyalgia and to identify potential mechanisms of PENFS effects. Further developing non-pharmacologic therapies for pain can help to improve quality of life and function for those suffering from fibromyalgia and decrease reliance on opioids and other drugs that have numerous side effects for individuals suffering from chronic pain.