You need a doctor to look after your overall health and a rheumy for lupus. I have an internist, 2 rheumys, and several other specialists to treat various conditions that have resulted.
A rheumy will have the most experience and best chance to treat lupus successfully.
If your insurance prevents this then you have to make the best choice...decide if lupus is the overriding health concern and find the very best doctor to treat that. That is usually a rheumy.
Bill