Get an x ray
If it was a fracture
there might be bone peices. Fracture is always painful and cause swelling. I dont think he is having fracture.Consult orthopaedic surgeon
because there might be hematoma
in knee joint that has to be aspirated. Apply crepbandage and apply ice ove it.
Do not sitvon floor, do not climb stairs nor sit in squatting position.
If does not get relieve.
Get mri done.
Get well soon.