I have it in my back, hips, knees, feet, hands. and jaw. I know, I'm a mess. Its pretty common for adult CFers to develop arthritis because our immune systems are on overdrive and eventually it starts to attack our joints, similar to rhumatoid arthritis. Taking calcium (which we should anyway), magnesium, and potasium can help. Its not uncommon for people with chronic pain to be deficient in one or more of those.