Could you be more specific, what areas of mathematics are you most familiar with and what have you done so far ?

Here is my suggestion. I might be wrong, but you might have 0 skills actually solving mathematical problems. Most of the math you see in Knuth (and CLRS) is Analysis, and it is not just simple Analysis: Real Analysis, Complex Analysis, Special Functions, Discreet Calculus, Variational Analysis, Combinatorial Analysis, Asymptotic Analysis. So it is not surprising that you are struggling.