How Can Severe Knee Pain And Tiredness Be Cured?

I have servere pain in my left knee after surgery 2 years ago. After my first surgery to put my knee caps in fixed position, I had gotten staff infection, and had about 4 or 5 surgeries after. I am in a lot of pain, and I tried staying off my knee, and I tried icing/heating it. It also pops when I move my knee at any pace.