I Have The Symptoms Of Arthritis In Numerous Joints Including

I have the symptoms of arthritis in numerous joints including both knees, my shoulder and thumbs. I have also been running a low grade fever for a few months. this has come on over the last year or so, I am 41 years old, obese and my father was exposed to Agent Orange prior to my conception and is currently suffering from Chronic Lymphocytic Leukemia. What could be causing my issues?