What Causes Painful Knees, Elbows, Shoulders And Neck?

I have unbearable pain in most all of my joints; knees, elbows, shoulders & neck. The pain is so bad that my whole body shakes like I am very cold cause of the pain. Just in the last 5 or 6 days the pain is worse then it has ever been. It started with my knees about 4 months ago and just in the last couple of months spread to my elbows & shoulders. the pain has worsened to the point that I have to us a cane to help me walk. What could this possibly be?