There's no perfect set of exercises, one size fits all. If it seems to be aggravating your problem, then I'd quit it. It's a muscle strengthening exercise actually, but the problem is that it puts your back into extension, locking that facet joint.
Or, try initiating the contraction, but not actually raising your leg.
Your knee pain could be a local problem but interestingly the Femoral nerve supplies the knee. And the L3 knee root supplies the skin on top of the knee, and inner lower leg. It's diagnosed using the Femoral nerve
stretch. Ask your chiropractor to test the nerve.
To test if that pain in the back of the leg is actually a sciatica, and not a hamstring problem, try this little Slump test for sciatica ...
Obviously I haven't examined you and it's clear your chiro is helping you. I think it would be wise to print this out and discuss it with him. Lot of quacks on the net!Go from facet joint pain and knee pain to other Chiropractic Conditions often treated…
I hope this has contributed.
Dr Barrie Lewis