A Lupus doctor is a Rheumatologist. Your mother is seeing the correct doctor for her needs. A high ANA can indicate that Lupus is very active, and immediate intervention may be needed to smooth everything out. Another test is an ESR (Sed rate) which can tell how much inflammation is going on in the body. This is a less specific test.
Stress can certainly send you into a flare! She does need to see a dermatologist, who can give her some cortisone based creams for her rashes to chill them out too. Prednisone (a steroid) is often used to stop a flare in its tracks too.
Just be as supportive as you can, and it sounds like you are! I am glad that you are asking lots of questions, it is so good to have information! Your mom should be proud of you for wanting to be a part of her care