I cannot feel it when simply standing or walking or daily things, I feel it only when I get into a certain position. It feels more like muscular pain/soreness rather than bone/spine related. It is above the hip bone and stops below the rib cage. The soreness/pain is over an area not in one specific spot. If I don't surf for several days it will kinda go away. I will notice it during a surf when transitioning from paddling position to sitting position. That movement crosses that "certain" position in which I will feel the soreness/pain.
Me: I am 17, 140 lbs, a little less than a half-decent surfer. I am very fit, I do bodyweight exercises (push and pull ups daily), I sleep on the floor, eat healthily. I stretch my hamstrings lying down with a belt and also a "butt" stretch in that same position.
My guess is that my lower back muscles are weak.