What strikes me is that you were improving, and then fairly suddenly began experiencing more and increasingly worse pain. As someone who had a similar experience, albeit mine was closer to the one year post-op mark when I began the backslide, I wonder if something has gone wrong inside? Shouldn't you call your OS and insist on an earlier appointment? And maybe this just is a variation on Josephine's comments, but who knows?
I was tested for everything under the sun - allergies to the replacement components, infections, loosening of the replacement parts - but it turned out the tendons surrounding my knee capsule had stretched and caused instability. It doesn't sound like that is your problem as your complaint is about the tight band feeling (oh how I remember that!) and not swelling and I had quite a lot of swelling from the instability, but still... worth considering.
I really hope you get relief fast.