Honestly i WAS good at math when i was in secondary school and high school. I don’t say this to make myself look good. I was seriously good. My grades fell to the top-10 range at least, exclusive a few tests at which i topped the chart.
Anyways, for some unknown reasons, my math-sensitivity dropped drastically once i went to college. My brain just stopped processing all the calculations and derivation and stuff. This explained my poor result in all the science modules at uni.
It hasn’t come back yet.