Have lupus had severe pain and burning starting from hip down to my ankle. had an x-ray didn't show anything. doc said it might be tendonitis on hip

Sciatica : Sle causes many problems. One of these is muscle pain as well as nerve pain. Usually when you have pain from the buttocks to the feet this is indicative of a pinched nerve in the lower back possible due to spurs or over activity. I would recommend an MRI of the lower back and possibly are your pcp and pt to help with treatment options. Even a podiatrist can help. Good luck.