Thank you for your query on Healthcare Magic.
Are the both knee joints having pain?
Any history of trauma?
Any history of swelling or fever?
These information is important to advise you in a better way.
Child needs further investigations like ultrasound
knee joint and MRI
of the knee joint to look for any local causes of the pain.
Nothing to worry and consult the Orthopedic surgeon with all the previous reports.
Hope I have answered your query.