Diagnosing August 25th Google ranking drops

[xoex]

Hi everybody,
More than one year ago I registered a previously hosted domain (which had still good links after years). I have worked on this domain for more than a year and It gets good rankings in competitive keywords.
In 25 August, I woke up and see it suddenly drops in every keywords. Its search traffic reduced by -90% suddenly and after 10 days there's no sign that it become better.
Recently I had no new links or any changes.
You can see stats for my website here :

[oi58.tinypic.com ]

Is it sandbox or penalty? I'm really desperate and don't know what to do!

[edited by: goodroi at 11:45 am (utc) on Sep 5, 2014]
[edit reason] Fixed image link [/edit]

[goodroi]

Sandbox is more about new websites that have yet to develop the quality signals that Google likes. It doesn't really apply to established sites.

It looks like you were more likely impacted by a change that Google made around August 25th. Several people reported big traffic changes (some were gains & some were losses) around that time in the August Update thread [webmasterworld.com...]

Have you looked at your backlink profile? What happened to your competition?

[GreyBeard123]

It’s a penalty...
One of our ecommerce sites that were slapped by Panda 4 completely recovered on the 25th August.
I think the same algo slapped your site...