Don't neglect the Core, it's all connected to the knee.
Have you twatted you knee on something or is it muscular? If the latter work on core, glutes, hip flexor, ITB, quads and calfs - strength, rolling, self-massage, always works things out for me.
Stepper and wall sits with Med Ball between your legs of it's the old problem.
if not 10 pints should help