What Causes Swelling And Pain In Knee After Total Knee Replacement?

HELLO,my name is Cindy...I had total knee replacement 8 months ago, had 4 months of tough PT and still am having issues. My knee is somewhat stiff and swells upon standing for any length of time. I stand at work and after about 3 hours swelling starts. I also have a fairly large bulge to the left of my knee cap.what is this? iv been told possibly scar tissue, have been seeing a message therapist for help. any suggestions