Age 2 Sore Knee Joint

My daughter is aged 2 and has been complaining of a sore knee joint for the past 2-3weeks.  At first I thought she may have knocked it but now Im not so sure.
She doesn't have continuous pain, I suppose it comes and goes.
Out of the blue she will say "mummy ouch,, ouch my knee sore", she doesnt limp, it can occur when picking her up, when she walks up the stairs, I suppose when bending it, anytime really.
Do you have any suggestions of what it might be and can you point me in the right direction of what to do next.
I do have Private Health Insurance for her, but would like to ask your advice first.  Many thanks,

[JainMD]

Hi,
How is your daughter doing?
I feel what she might have is septic arthritis.
You need to get her imaging study done to see for joint space and soft tissue status. You can get X-ray done and also MRI to see for pathology. MRI would be bit difficult as your kid might not tolerate the procedure as it takes long time.
You need to also start anti-biotic if proven to be septic arthritis.
You need to consult an orthopedic surgeon and decide regarding further management.
I would be interested to know the progress.
Keep me informed if you have any queries.
Bye.