I would look for a second opinion from an orthopedic surgeon in an academic practice that is "out of town." It is rare that a surgeon or any doctor will be helpful to a patient that has a problem that may have been caused by a colleague or a physician in the same city or community.
These physicians, who are approached for a second or third opinion, worry about being dragged into a lawsuit or some other unpleasant situation. Lawsuits can be time consuming and, of course, will make other surgeons in the same time view him or her with askance.
This all is not fair to patients.

I would find a specialist in knee replacement, ideally a surgeon in his or her mid 30s to mid 40s with a solid pedigree at a medical school and/or residency. Also, look for someone who uses the Mako robotic assistant. They will not turn you away.

I have no doubt your X-rays look fine but that's not the whole picture and the surgeon who turned you down is not worth seeing. It might be scar tissue but unlikely if you've done all the rehab and continue to exercise.

Is the pain to the inside or outside of the knee? That could be ligament strain or damage. Another less likely possibility is a Baker's Cyst behind the knee. It's hard to tell without more info. Your first Dr. should not be giving up so easily. That said, a small % of TKR patients do experience lingering soreness and stiffness.

I would find a real specialist and get his or her opinion. All the best to you.

You need to get a third opinion! If that doctor gives you the runaround then keep going to different Orthos til you find one who can help you. The one that told you he doesn’t do a second opinion should be a red flag that something is seriously wrong here! You have to be your own health advocate as I have found that no one in the medical profession at least around here will be! Do not give up!