Julie, I'm glad you have a good massage therapist. I hope you continue to benefit from that, because you certainly do deserve a break.
I got a poke from a mutual friend to comment on piriformis stretches. I don’t think I’ve ever gone into it in detail, so maybe it’s time for that.
Here are some posterior hip muscles, including the piriformis:
The piriformis has two broad functions. When the hip is flexed past 90 degrees, the piriformis adducts and internally rotates the femur. When hip flexion is less than 90 degrees, the piriformis abducts and externally rotates the femur.
So, there are two ways to stretch the piriformis, based on these modes of action. If the hip is flexed past 90 degrees, you abduct and externally rotate the thigh. This is the stretch that we are all familiar with.
The other option is internally rotate the thigh, with less hip flexion. That looks like this:
To deepen this stretch, move your feet away from your bottom and apart from midline. It's okay for your knees to touch when doing this stretch and I generally find that to be more comfortable.
Unfortunately, I wouldn’t consider either of these stretches to be particularly knee-friendly.
This one might be better for your knee, but not if you're pressing on it with your hand, like this guy. Press on your thigh instead, if you need to.
You can even rotate your spine, if you have some flexibility there:
With these last two stretches, try varying the flexion of the both the knee and hip to try to get the stretch where you need it.
Good luck and let me know how it goes, if you try any of these stretches. I may have some other suggestions.