Work your knee gently :-)

Everything you see is done with kindness and caution:

This is an interesting one because it looks counter intuitive.  Make sure you use a PAD where you kneel, this is excellent for hamstrings:

Be careful with this one and keep the legs apart enough to have a solid balanced position:

My friend and rival did this exercise, more for core put a strong core does not exist with strong legs:

This one is fun:

These were my staple stretches:

The other thing we have to think about is whether some rest would help.