My worst pain... that's hard since I have two very troublesome spots. My knees and my upper to mid back. Yet, if I really got to choose, I will say my knees. I have a sprained ACL and PCL and some other issues going on in. That's in my left knee, but my right knee is feeling the exact same way as my left knee did when I had to have it looked at. I know my body, and I know that my right knee is catching up with my left. My back, though, hurts if I sit up too long, when I lay down, prolonged walking, etc. A physical therapist did an initial exam on me and found I lost range of motion in my neck as well as I do have some form of Kyphosis. I am constantly in pain.