Tendonitis after TKR

Hi everyone-
I had my left knee replaced 20 months ago and have had sensitivity in the front inside of the knee since the beginning. I have been able to deal with that. Now I have had a big change with what my Dr. thinks is tendonitis. It became so stiff I couldnt walk without a cane and a bad limp. The stiffness is not so bad, but I have sharp pain that goes across the front under my knee cap. Its the kind of pain that stops me and is honestly scary. It used to happen every few days and now it is everyday and multiple times. I cant walk very well at all as this has affected my right leg by compensating. I am now using a scooter for most things (work, dog walks, medical).
I am wondering if anyone can relate to this or has had something similar? I am also getting a bone scan to see whats going on.