What could this be?

[LittleFish]

I have a weird problem, and it's starting to get to me. Sometimes my mind does this thing where it basically locks up, and it's almost like the part of it that's supposed to interpret information stops working. Someone can be talking to me in plain English, but if their sentences contain more than a few simple ideas, I don't understand any of it, and I have to ask them to repeat themselves. It also happens to me a lot when I'm reading. I can read an entire page and not remember a single detail even if I'm trying really hard to focus. When this happens, I get dizzy and have a dull headache. I feel very similar when I'm asked to put things in order or solve logic or math problems. I can't do puzzles to save my life, riddles are impossible, and just looking at word searches gives me a headache. And despite having taken piano lessons and studied music theory for the past five years, I'm barely sight-reading at an elementary level while I'm playing intermediate.

It's been this way since I was little; when I finished kindergarten, my parents had to put me in a special class because my motor skills were crap, and it took me until I was almost five to learn how to do basic things like tie my shoes and cut with scissors.

I'm not sure what to do about this. It makes school work really hard. I've always done well, and I managed to hold up a 4.0 GPA last year. But I'm just not sure how much longer I can keep up with this. It makes me feel really pathetic and simple-minded. What do you think it could be, and should I talk to a doctor about it? Maybe tell my counselor?