Most autoimmune diseases are not really diagnosed by tests, but by a collection of symptoms
. For instance, Lupus is diagnosed by having more than 4 of the 11 symptom checked. https://www.webmd.com/arthritis/psoriatic-arthritis/qa/what-are-the-11-signs-of-lupus
Since you say her ANA has been consistently high, I would look for a rheumatologist who is more familiar with autoimmune diseases. One way to do that is to look at groups like www.lupus.org and find the chapter closest to you. Then check with them to see what local Drs are active with the organization.
I've found it's best to be very careful when presenting outside ideas to Drs. First let them gather the facts of her symptoms and figure out what their ideas are. Try them out, they are the experts. Suggesting things too soon actually limits what they might consider, as well as can often offend them. Drs are people, too!