TKR Re-hab

I had my surgery on 07/30, and overall am doing reasonably well.
However, I continue to have dull pain on one side of the knee that gets sharp every now and then.
I can only drive for half an hour to 45 minutes before the pain gets to great from lack of movement. Finally, for the past six weeks I have had muscular pain in both thighs. I ride my bicycle a couple of miles each day, do amile or so on a treadmill, and about 50 leg pressesof 60 lb wights every third day. Am I doing too much or too little exercise contributing to this continous discomfort?