Can't get good at math again

Every time I learn a new thing I forget it, I spend months doing derivatives and I'm still here struggling, I don't know if it's a lack of interest or something else. I used to score 19/20 in 10th grade, but I was having family problems and on the exam day I started shaking due to huge accumulated stress while doing the math exam, and scored 11, never got my level back since that day. Maybe it's that too. Spending so much effort and still being bad is genuinely frustrating. Did you live similar situations?