Most Helpful Guy
The exact same thing happened to me, I had blue eyes till I was about 10, then they turned green, now they are fully green. It's really funny you ask this today. As a matter of fact last night I read some fascinating articles about it. They believe all eyes start out as blue. Some study called iridology (some people call it bs) states that our eyes turn green due to a more acidic body which basically puts a yellow layer over your iris. In order to have blue eyes your body would need to be more alkaline. Apparently eating a diet with loads of fruit and veg (70% / 30% fruit + veg / meat ratio) for a year or so can turn them blue again. Some people swear by it. I'm thinking of trying it to see for myself.
As for the brown spots, I found a video which attempts to explain them (sounds a bit cheesy to me) in what is called Bio-Optic Holography. They won't let me link here till I'm level 4 but I'll attempt to link you a vid, you will have to type it in your browser. www(dot)veoh(dot)com/watch/v6391292ZjW4M8y5
Interesting stuff but I the vid sounds a bit far fetched to me, you be the judge though.