I am also glad that your doctor went above and beyond by running the additional test. Especially given the fact that, as Tgal mentioned, there is a form of Lupus that is sero-negative. Lupus comes in many forms and no two persons will have the same symptoms. Also, as you noted, it is not uncommon to have more than one overlapping issue occurring at the same time.
We are here to help you as much as we can, so this is a safe place to vent whenever you need to.
Please keep us posted on your test results and decisions made by you and your doctors. Best of luck to you.
Peace and Blessings
Look For The Good and Praise It!