What can cause ANA titre of 1:2560?

Hi everyone,
I got really sick back in January and have been struggling to get a diagnosis or treatment. I've read quite a few chat threads on this site for some time but have never posted. I have a question no doctor has been able to answer. Maybe someone in this community might have some insight! In May a doctor tested my anti-nuclear antibodies (ANAs). The titre was 1:2560. I know ANAs can be elevated by autoimmune diseases, cancer, and viral/bacterial infections, among other things. So far, doctors haven't been able to figure out what's wrong, despite a host of weird symptoms and irregular tests. My question is: How likely is such a high ANA to be associated with an autoimmune disease? I've repeatedly read that the titres caused by viruses and bacterial infections are usually "mild", presumably <640. Is that true? Doctors have ruled out cancer, they don't believe it's a bacterial infection, but a virus is always a possibility. Can chronic viruses like Epstein-Barr cause such a high ANA? Has anyone else here personally experienced that? I've seen a handful of doctors, but most have been dismissive and unhelpful. I'm really frustrated. Hopefully someone here can provide some clarification. Thanks!