I advice is always keep changing .... put news things ... theme change .. because google changes strategies. Maybe the previous google traffic strategy was meeting your side look but not the new one.
there's a couple of factors that may have played. -you don't update your pages -your not building enough backlinks -your sites load time may have slowed down, therefore google ranking you low -you may have been suspended by google best thing to do is sign up for google webmasters and check things out.