There is a "muscular" condition called "Tendon Guard Reflex" that can create a lot of pain, discomfort, and even injury along the backside of your body in areas of the low back, hamstrings, and calf muscles. This condition results not from a physical issue but from a psychological or mental stress situation. Here's some interesting history on the history of back pain and Tendon Guard Reflex and how to think about this condition differently and why it's so important for our youth to learn these "self-care" methods early in life too. For more information on the Kraus-Weber Test that I referenced, please see this Bonnie Prudden history link:
https://theleanberets.com/approved-resources/k-w-test *Photo Credit: Bonnie Prudden archives showing Bonnie administering a portion of the Kraus-Weber Test.