How old is your site?

Google dance?

Any mischievous SEO tactics?

You can check your analytics stats and see if there’s some reason why traffic is down. Decreased in traffic often occurs when a site has low-quality content (poor spelling and grammar, articles which are irrelevant to your niche, offers no value to the readers), overoptimized keywords, low quality links and duplicate content. It could also be a dance. If it is, then you should continue adding good quality articles to your website and update often. Build links slowly and continue building to keep the link velocity.

I am also seeing some major changes for the keywords that I track. My sites are bouncing like S***

due to page rank update

Here is a discussion you guys might want to look into
May 2013: A Massive Algorithm Update at Google?

I would rant, but I've come to the conclusion that Google will always protect the big brands. White hat SEO is dead.

There's an active webmaster thread that noticed the rankings shift this morning--looks like a penguin update, sites that are most affected were also afected during first penguin update.

Google Updates and SERP Changes - May 2013 Google SEO News and Discussion forum at WebmasterWorld