Having an existing autoimmune disease (Chrons) will give you the same symptoms as what we have. Unfortunately, they all mimick one another. You can definitely have a positive ANA with Chrons or any other AI disease.
Interesting that you have sacroiliitis. So do I. I have it BAD pretty much all the time. Headaches are something I live with on a daily basis too. It's probably a wise thing for you to keep on researching the Lupus possibility considering your Grandma had Lupus.
Have you had any issues with your blood? Low platelets in particular? An enlarged spleen can cause that to happen.
I would get a second opinion from another rheumatologist. Blood test results aren't the only factor taken into consideration for a Lupus diagnosis.
Good luck and keep us posted!
Moderator of Lupus and Fibromyalgia forums
36 years old, diagnosed in 2000. SLE, Fibromyalgia, APS, Sjogrens, Raynauds, Thrombocytopenia, Vasculitis, Stroke – 2002, Bilateral sacroilitis, Clinical Depression/PTSD/Anxiety/panic disorder, Optic Neuritis. Prednisone, Imuran, Plaquenil, Coumadin, Cozaar, Zoloft, Didrocal, Seroquel