Always had a slight sensation numbness in my back along the line where my bra strap falls. Didn't notice it until I was a teenager. Since then, I've noticed it slowly spreading down my back. There is no tingling, just numbness. When I rub my fingers across it, and they come into contact with skin that feels, along the edge of the numbness it hurts. Like scar tissue with nerve damage. I have had no back injuries or spinal injuries, feel nothing more than common back soreness from tasks, and I don't believe I have anything wrong with my discs. What could it be?