I had no back pain prior to doing SFQ. I try to keep my weight balanced on my feet, knees slightly bent, pelvis tucked forward, shoulders relaxed. I experience lower and upper back pain. The back pain is a relatively minor issue compared to my perceived lack of any benefits, and my inability to go into the emptiness. Monkey mind never ceases, which makes an hour-long session almost unbearable.
Thanks to all for your replies.