This sounds so dumb.

I dont understand how to phrase this without sounding like an idiot but I'm gonna write it how I feel it. I feel like I'm actively getting dumber, specifically relating to school. I've never really worried about academics but this year I'm worried. Im sorry if this is vague but I don't know what I can give without giving too much. Im 16, male and I have 4 heavy classes this semester, last semester I only had one heavy class. I think that might be what messed me up. I fear I'm going to fail some big upcoming tests and I need someone to explain what's happening to me.