Could also be fibromyalgia. They're two diseases you get diagnosed with if they can't figure anything else out. I don't know much about lupus, but if it functions similarly to fibro and I'm pretty sure it does, then one of the best things you can do is manage the inflammation in your body via diet. Food intolerances, stress, or anything else that triggers inflammation will likely also trigger a flare up. For my wife any time she eats gluten she's out of commission for at least a day if not more