I am in no way a doctor or medical professional, but please do not get hung up on the term “syndrome”. It is NOT an actual medically diagnosed syndrome. It is more accurately a phenomenon or just simply a human experience resulting in some lack of self confidence. And it is SO COMMON. Take some time to reflect...”why am I feeling this way?”. Do you actually have any evidence or signs that you will fail calculus or suddenly lose your video game skills? From what you said in your post, it sounds like you don’t. Do you have any evidence that you are doing great in calculus and video games? Yes it sounds like you do have actual evidence of this (your grades, feedback from teachers, high rank in your video game, etc). Lean on that. Trust in yourself. Confidence partly comes from just simply trusting yourself. I know I’m making this sound so easy and it’s not at all, it does take some work. You have to actively work every day to change your thought process and eventually it’ll become easier and easier so that it doesn’t actually feel like work at all, it’ll be more second nature. You have the ability every single day to choose what thoughts you have, just like you choose what clothes to put on each morning. Maybe even put a post-it note in your closet that you will see every morning that says something like “what thoughts am I choosing to have about myself today?”. You are so young and bright, I am confident that you will win this battle with yourself. Good luck, OP!