I Am Noticing Mild Tenderness To My Pip Joints On

I am noticing mild tenderness to my pip joints on both hands, which has developed gradually over several weeks, and now I am noticing nodular growths appearing on several of these PIP joints. I also have one knee with an effusion (unrelated to trauma) and one elbow that is tender, especially first thing in the am. No trauma to elbow, and no nodules noted. I am worried about RA, but have no family hx of this. What else could cause bony nodules on PIP's? Thank you.