A penetrating injury
to the knee, should not be taken lightly. The description given suggests a collection of fluid, (blood) inside the knee. Thus there is a swelling and a pulling sensation, pain spreading unto the toes.
So, please do get in touch with the Ortho fro an adequate assesment.
In the interim you should put the child on bes rest with no weight bearing, keep the knee in a semi-flexed position, ( partially bent,achieved by keeping a rolled towel, below the knee.) A cold
compress( crushed ice in a plastic Bag) for local fomentation along with paracetamol
would be helpful.