Thanks for posting your query.
You might developed synovitis
right knee. Synovial tissue on inflammation secretes more synovial fluid
so you feels like pouch of fluid above your knee.
I suggest you to consult an orthopaedician nearby for a detailed examination. your doctor may aspirate the fluid and send for microscopic examination to know the exact cause.
Meanwhile give copression by crepe bandage and you may take anti-inflammatory drug like motrin
to reduce pain and inflammation.
Wishing you good health....