Normally, when you a MUA your out time starts at the time of the MUA, not the replacement time. So, that means your knee is really only 3 1/2 months old. When you have a MUA your soft tissues are damaged again and your knee becomes inflamed almost as much as a replacement knee. Give your knee lots of rest, ice and elevation and I bet the pain will subside. It's great the the MUA worked for you, but you have to give your tissues the time they need to heal all over again.