Exactly why I have been asking people about their selenium intake. I havent been here very long but its one of the trends ive noticed. People start Iodine without selenium, show initial improvement and then they get worse. In most of these cases when asked, they werent taking in any, or limited, extra selenium.
Also keep in mind just because you live in a green state, doesnt mean you food is from a green state. For example many of the green states are in the midwest, but chances are if you live in a northern grean state the fruit and veggies you eat in february arent from your state.