i have no way of examining you over the internet to give you a definite answer (only your doctor can do that) but one possibility would be a common (and temporary) condition of pre-teens and teenagers called sever's disease. you can look this up on the internet and run this possibly by your doctor.
i'm thirteen years old and whenever i run or even walk my heels hurts. it is a sharp pain and consistant. what's wrong? . i have had pain in my heels for about 2 years. it has been better at times and then got worse at times. it is a sharp pain that sometimes lasts for an hour or more during and after exercise.