Knee jam can happen due to osteophytes which get obstructed between the joint and cause inability to bend the knee joint..
It usually recovers as soon as the osteophyte is displaced from its position.
Next Steps
You can use a Long Knee brace for support to avoid load over the knee joint and reduce pain.. You can take analgesic and anti inflammatory tablet for reducing pain.. Physiotherapy can help
Health Tips
Avoid overbending of knee, avoid sitting down cross leg, avoid use of Indian toilet