I have had a red itchy rash on my legs and now my arms for several month, I have pain in my legs and sometimes my legs give out. I have been to the doctor several times, they have taken blood, and I ve had a chest x-ray. They don t know what this is. They had me on doxycycline for a week, it got worse, then the dr put me on prednisone for a week. the prednisone helped for a few days then it came right back. Is this Lupus?