Page 2 - OKay, should I panic now or later?

so as I'm going through, I seem to have been 'penalized' for all my major keywords and combinations.I can't believe that it's not a penalty of some sort to have knocked me way out of the ballpark for so many of the KW's I worked hard to establish for my site over 6 years by clean programming and exchanges...and why out of the blue after the current page was ranking well since its overhaul in April/May really bothers me...
So my question now is how can I regain Google's 'trust', so to speak.I still am unsure how this happened, so not sure where to start to remedy this.Would just focusing on links help bring me back?Should I re-do the content of my main page?I'm ready to pull my hair out but would appreciate any help again... thank you for all the responses so far.