It could be like mine, caused by L5 disc problems. I have had surgery once already. Prior to my surgery about 15 years ago I could hardly even move. I was pain free for many years but the last couple of years the pain has started again in a much milder form. The surgeon told me I would get about 10 years out of the surgery.
On a bike the forward bend position opens up the space at the back of the two vertebrae adjoining the disc and it tends to relieve the pressure on the nerve.
Ditto on the forward bend position. As long as I cycle, my back is in good shape. When I can't bike, my back lets me know. Went to a back specialist a while back that explained how it worked. Just what you said con. And I thought I was the only one!