A 32 year old woman comes to her primary care provider for a return visit with the chief complaint of joint pain and swelling for several months. At first the pain involved the left wrist and elbow and the right knee, but gradually became bilateral and now involves the metacarpophalangeal and proximal interphalangeal joints. Every morning, she has stiffness that slowly gets better after a couple of hours, but the generalized fatigue and weakness lasts all day. Her eyes often feel gritty and dry. She has had some weight loss over the past few months. There is no skin rash or oral ulcers. However, the oral cavity appears overly dry. There is no history of fever or diarrhea. On examination, the affected joints are bilaterally warm, swollen and tender. The rest of her physical exam is unremarkable. What is your presumptive differential diagnosis