Pain behind knee

I have an achy pain behind my knee for quiet sometime. I've noticed that I can't do a full range of motion when doing a Slump Test, and SLR (toes pointed towards head). When I turn my foot inward the range of motion drastically reduces. I have no pain at all in my back when I do the two tests, I do get increased pain behind the knee when I do those tests. But, once I have done the Slump test or SLR I do get better range of movement. Thou the pain continues.
I also have hyper mobile knees.
I've had an MRI on the knee and all is clear, I've had a MRI on the back and there is a minor buldge at L4/5 but does not touch the nerve.

When I do a Tibial nerve stretch I don't have full range of movement. (seated in chair, chin in chest, leg raised in front, my foot does not have full range movement)

Is the problem coming from my back or more locally behnd the knee? Would my hyper mobile knees be causing it? Is there any exercies to reduce/control the knee range of motion.

I think only a professional can tell you that after careful evaluation.