Hi welcome to Health care magic forum.
Thanks for calling.
It appears that you might be suffering with rheumatic or rheumatoid arthritis
, or may be simple arthritis. To confirm what type of arthritis you should consult an orthopedic surgeon.
You may have to undergo, C.T.scan of knee, R.A.factor , besides other routine tests for cofermation of the condition.
Wishing for a quick, and comfertable recovery.