It's not a mystery and actually completely predictable for Darkcoin to be dropping.   You need to understand that when Darkcoin first went up it had ZERO competition and was the only game in town for anonymity. Now that entire landscape has changed and the price is coming back down to reflect these new conditions. It's a tough sell to claim that Darkcoin today should STILL BE 700% more expensive than other actively developed anon based coins, but back when it was the only one, this was perfectly reasonable.
This is why Litecoin and Dogecoin also have bloated marketcaps and why those coins have also been declining daily.
As a case in point, Dark is still, even today 500% more expensive that a presumably high flying coin like Vericoin. All while Vericoin, arguably, offers more to it's users. So considering that, you can see why the Dark chart has turned decidedly negative in recent weeks.
I've been a Darkcoin devotee since February but I sold ALL my Dark several weeks back when I came to this conclusion and I put it all in VRC. I would recommend you do the same if Dark fails to rebound strongly off this double bottom and start a new trend higher.  Also keep in mind that this is a coin priced at a premium so there is still a long way down to fall if support breaks.