Could I have a learning disability and just now come to know in college?

Hey, I am a civil engineering student, and I was working full time for 3 years while attending school part time at night, I am done with my general education now, but since I got laid off last year, I am now going full time and I am noticing some things that I never had before as I am getting into more challanging classes, its not that I am dumb, I believe that if you apply yourself you can do anything, I am just having some trouble making connections with water quality - pretty much math word problems. and I can study for hours on hours and think I understand but when I take the test I just blank, and I have been putting 100% in my classes and the grades are not showing my effort, I am wondering if I might have some sort of learning disorder, when it comes to reading and regurgitating, like in my geography class I am fine, its like the difference between the brain working and putting things together and the brain just remembering words.