Significant ranking fluctuations in SERP

[heyitsjoe]

My site's URL (web address) is: http://www.green-card.com.au

Hello,

My site has been around for 5-6 years now, and recently it is  experiencing some very significant fluctuations in rankings for its main keywords.
For example, the ranking for "DV 2013" can be 4-5 on Google.com one day and impossible to find the next day.
This also relates to all long tale keywords that are made up of DV and 2013. This is just one example but it happens with may other keywords as well.
All in all, the change in traffic can be as drastic as a 95% drop and a few days later all of a sudden it's back.
I'm concerned why this could be happening, and whether it signals that we have to make some changes as it occurred 3 times already.
I have recently added some country specific content that discusses how the green card lottery is relevant for each of those countries and have had some backlinks placed on edu wiki sites.

Can you please advise what could be the cause for all that?

Thank you.

Joe

[C.Rebecca]

Is there a drop in traffic too?
I think your niche is competitive which is why you are facing significant fluctuations in SERPs.

Check for quality of backlinks. If you have backlinks from junk and low quality websites, Google might have devalued them.

Check your Google Analytics account and pin point those keywords and pages for which traffic has dropped.I would suggest you to track your keywords using Google analytics since it will help you give a complete report of keywords due to which your traffic dropped.

[Kanchan Srivastava]

After Google Panda update, Google has down keyword ranking of several websites . so check your website content and off page content which should not be duplicated .