Pain on mid spine where bra strap together lie, pain when touching it, redness and a little pain when bending back. 19. ?

Irritation: from the bra hooks could be the cause, at your young age, but a local infection is also a possibility. Assuming you have had no injury, you could try wearing a sports bra, keeping a little disposable hand warmer (from sporting/hunting store) on the spot and watch it for several days. If redness or pain get worse, or you get a fever or chills, be seen right away. Good luck!