I basically have the same thing as from little as i can remeber. I am now 13 years old. My brothers girlfriend is a physiotherapist, and she works in london on harley street so she knows her stuff. So basically she look at me and she said it was posture, i went to the doctor and he said posture but he also said that he had never heard anything lt before. So i asked my brothers girlfriend what i should do, and she said to keep your back straight and she showed me some work outs to do. You lie down on your stomach adn lift you head up, and took your chin into your kneck, to test if your doing it right stick out your head out again and then in, keep doing that and it should look like your a cockral. when you think your in the right possion, hold it in for 60 seconds 3 times a day and it should really improve. also look at a mirrior, and check out your posture, practise by pushing in your bottom and your back straight.