Is it mental or physical? And how do I make it stop?

Okay, well it seems like you’re taking way too long on your homework, however you mention that you have had to teach yourself? Thats why! Its extremely hard to have to teach yourself a subject, especially math for that matter because the teachers teach you the tricks and how to get the answer with the least amount of time and the most effectively. I understand what you must be going through, I’ve had to teach myself stuff too and it isn’t easy, it takes a lot of time. I just think you need to be patient. Keep on doing what you are doing except maybe make a time schedule. Tell yourself, I will spend no more than this much time on my math, if I can’t complete this math problem in this many minutes, I will move on. Then when you get to math class ask your teacher to help you with the ones you couldn’t get fast enough. Trust me, this is the only way you can get to all your subjects in time, with a time schedule. Also if you feel drained out or exhausted, take a 10 minute break after an hour of studying and this really helps in picking up your energy. Eat a snack, drink something, or even just stretch or use the bathroom. You will be surprised at how much energy this will give you. Best of luck.