If the above suggestions are helping, you may benefit from getting Pete Egoscue's Book Pain Free, and doing his "E-exercises" .
"The key is a series of gentle exercises and carefully constructed stretches called E-cises. Inside you'll find detailed photographs and step-by-step instructions for dozens of e-cizes specifically designed to provide quick and lasting relief of:
Lower back pain, hip problems, sciatica, and bad knees."
Hopefully Posture Guy, who posts here and is an Egoscue therapist will weigh in.
One of the exercises in the above book are "cats and dogs".
Suzanna McGee, who posts here as sxftlion, has a good description of the exercise and why it helps:
Cats & Dogs Exercise Helps Painful Shoulders, Elbows, Wrists, Lower Back and Knees http://www.tennisfitnesslove.com/201...ack-and-knees/