welcome to hcm.
Its my kind request to you to stop meddling with the swelling for it could be anything say a chip of Patella/tendon/etc.
Kindly mention ur age, sex, physical activities, job profile for a proper assessment.
It seems like the inflammation has subsided leaving behind this.
I kindly recommend you to take a Plain Xray of the Knee joint (AP view; Lat view & Skyline view) to rule out any fracture
of the Patella bone and consult an Orthopaedician for an opinion and further management (a MRI
of the knee joint would also be taken if not otherwise).
Do not stand for long durations and also dont keep ur knee bent for long durations.
avoid walking long distance and I would strictly advise to avoid running or jogging until U rule out with the orthopaedician.