Randomly dizzy/ nauseous and trouble breathing?

About two to three months ago, I started having this problem where I can only breathe fully when I yawn. At first it wasn't only where I could breathe fully by yawning, but now I can only breathe fully by yawning (that happened about a month ago).
Also, I'm not sure if this happened before or after the breathing problem, but I get randomly dizzy, my eyes get "fuzzy" (like a blueish hue to everything), and then I feel really disoriented for a while, like I'm in a weird daze.
I've also had a lot of trouble collecting my thoughts, remembering things, and I have become more irritable. This is really unlike me because I used to be a really fast thinker and had a really good memory (like four months ago I was). My grades have also gone down (went from a 99% down to mostly 97s and I have to try more).

I'm sixteen, 5'8", and about 125 pounds. I eat like a normal person, and I'm really pretty average. I do wake up at four a.m. (I get 6-7 hours of sleep), I drink 3-4 cups of coffee daily (but I drink it black), and I drink about 96 oz. water (I have a water bottle, and, yes, I keep track), but I'm not really sure if that would have anything to do with my problems. I've never had any serious medical problems, except for Walking Pneumonia when I was six, which isn't even a serious problem.

Thanks!