I've been doing an automated strategy that has been profitable for 2 years and all of a sudden this month it has been catastrophic in losses. I did 4 years of backtesting with nothing that suggests this would happen. What the f*ck do I even do now? My account is destroyed. I'm not sure if I should just quit or attempt a new approach. I followed my strategy to the letter and the backtesting was done in a precise and logical manner. How does a system all of a sudden do that?