I've been penalized for my main keyword, it had been up and down (first rank, down to page 2, first rank, down to page 2) but after several months of the dance, now my site ranks nowhere for that keyword (not even in top 1000). So I know i've been penalized. However Im still ranked 1st for the another main keyword (has been consistently doing well there). So I wonder what to do now, should I keep building backlinks or what? Can I get back my ranks and how to do that? I'm afraid if let's say I request reconsideration I would lose my another main keyword rank which has been helping me to make some good amount of money. Any suggestion guys?