Have you had an MRI of your knee?

Have you tried putting a Lidoderm behind the knee, on the thigh side of the bend?

Knee pain can refer like you describe.
When I had mine, it was the front of the thigh...deep pain.
But if you have a ligament damaged in the accident, the pain could refer elsewhere. It was odd that most of my pain back in those days, was not in the knee but in the thigh instead.

There is a pressure point on the lateral side of the knee just about an inch or so from the bend. If you sit with the knee bent and press this spot....it is very painful? That is the meniscal trigger point, and mine was very tender when I had that ortho problem.

My knee healed up finally---after several years ...but I don't have the same degree of pain I had back then (it is a bit stiff and does not like stairs, and I cannot do bends with it). The MRI did not show the suspected tumor/cyst the Ortho was looking for, but did show synovitis. So I had a steroid/Marcaine shot under the kneecap, and that helped a little.

Mine hurt so much at night, I worried I had bone cancer! So don't discount the knee as a source of problems, esp after an accident.