What Could Cause Intermittent Swelling, Stiffness, And Weakness In My Knees, Hips, Neck, And Arms Along With Sciatica?

I have always been healthy and active. Then one day my knee started swelling, then the other knee. They don t bend. Then I got sciatica down both legs. When I sleep it gets worse and my neck gets so so stiff and my neckbone hurts. Lately I feel stiff in my hips. I can hardly get out of the car without holding on. Muscle weakness. And the muscles in the backs of my arms feel stiff. I can t raise my arms all the way. And then it all goes away for a few hours sometimes.