The pain might be because of prolonged sitting when you keep your knees bent for long periods, it creates increased pressure in the patellofemoral joint.
Next Steps
Do not keep your knees bent for long periods at a stretch.
Take a 5 minute break every hour to do mild stretching exercises.
Do not sqaut or sit cross legged.
Do not sit on the floor.
Use warm water bags and pain relief spray.
Use a knee support.
Consult if pain is too severe.