Are you affected from penguin or panda before? OR If you have not looked back to the links coming to your pages, it’s really time to revert and check if it was done appropriately.
The time is to evaluate your linking with all recent SEO trends to make your pages saved from any google penalties. If you have used some link building services far before, you are really on the risk of failure sooner or later because the trends have now been changed and you need to clean up your bad backlinks before they make and severe affects.
Make your back links crystal clear and always care for the relevancy of the content on the site/pages linking to your pages. Moreover, the pages linking to you should not be linked from pages irrelevant to their content because if they are penalized, sooner you might get the same consequences.