I'm 15 years old male athlete. Whenever I do any sprint for any distance I get sharp pain below my knee that last for over a week. I also get this pain when I'm walking around all day, but in that case it is less severe. This pain causes me to limp on both legs. Cause very bad pain whenever it is bent and pressure is applied. I have a lot of trouble walking up steps with this pain. I have had this since the beginning of workouts for football (We had to run about half of a mile for warm ups). And now even when sprinting short distances such as 40 yards I still get the same harsh pain as if I were to sprint 100 meters. Any distance causes the pain. Walking is fine, Jogging causes pain, sprinting causes excruciating pain that gives me trouble walking. I had to take 800 mg iBuprofen for my back but this also reduced the pain while running. Can anyone give me a clue what this pain could be? And how to fix it?