First of all, this is not your problem. I can only say that your head teacher is sick. Have you ever changed your mind? Maybe your class teacher is encouraging you to make progress in a more extreme way? His "special" care for you may be that you need that way to push you. Everyone has his own way of progress. Although your teacher's method is wrong, you have grown up after so many years. Forget it! Find a free time, go and see your teacher and tell him that you have done a good job. . . That teacher deliberately picked on you, so now you are enough to make him regret and feel guilty. If he had been kind to you, he would have been pleased with your achievements. . . You can also ask the teacher directly why I gave you "special care" in the first place. I believe he will give you a reason to let go. . . .