Autoimmune diseases, such as Hash and Lupus, often go "hand in hand".
I have Hash and 10 years ago was also diagnosed with UCTD (undifferentiated connective tissue disease), which can be a precursor to Lupus. In the meantime, I discovered through my own research that I have CFIDS, not the lupus-like illness. The problem is that CFIDS and Lupus symptoms look very much alike. A rheumatologist is needed to determine if you have Lupus, but I'm also followed by a rheumy for CFIDS.
What I'm trying to say is that it may take awhile for you to sleuth out, and feel assured of, your proper diagnosis. I wouldn't just rely on MD's to tell you what is wrong, though. Definitely you need the diagnostic tests, especially to determine your ANA level (through blood work), which is needed for the Lupus diagnosis. But you might also do a lot of research on your own.
All the best!