Why does my leg hurt to touch?

I have had 3 knee surgeries (on same leg). ACL problems. The last surgery was a cadaver graft for the ACL. All of a sudden, my knee has started hurting very badly. It is burning on the inside and my whole leg is hurts all the way up to my . It hurts to even touch my skin. I have it wrapped in an ace banddage and heating pad. Could it be that it is "messing up" again?? What can I do to stop it? I can't sleep at night from the pain. During the day, I just get through it. Thank you in advance for any advice on this.