Strange outcome after TKR

Hi, not sure if this is still an active site but here goes. I had a scuccessful TKR on my right knee, 12/17/11. I had one event with intestinal bacteria but fixed that with Floragen. After about 10 weeks of serious pain, I was pain free and very happy I had the surgery.  In April I was in the shower and my leg seemed to shift and then I was in serious pain. My surgeon found a piece of the unbreakable cement, had broken and was traveling. I had a scope to remove the piece May 2nd. About 24 hours after surgery my knee locked, it has now hapened a second and third time and each time it lingers longer and hurts worse. Has anyone ever had that happen? After the TKR everyone asked if my leg was locking and I never had that issue. I was really happy a couple of weeks ago, now I have to keep crutches with me. Thank you in advance for any help.