Buying Strong traffic drop, can't understand source, hiring expertise in finding

Hello !

I have a website whose traffic suddenly fell, however I can't find WHY it's happening.
Seems like Google is sending as many visitors as of usual, social visitors are stable, no server issues, no blacklisting of the domain anywhere, in the google webmasters area there are no warnings and google tells it's showing the site to the same number of people as before... It's like direct traffic fell, bam!, without reason. I suspected it might be related to Google Analytics, however a second stats engine shows a comparable drop (statcounter), and the earnings with my ad network fell in the same measure.
Such drops have already happened in the past for a few days (not as sharply as now), and, there too, I couldn't figure out why. Direct traffic dropping like that, it's a complete mystery to me.

--> Would you know if there are people that I can hire for their expertise in analyzing, in understanding Google Analytics stats ?
I hope someone with more expertise, skills and experience, can understand what is happening, and if there's a way to fix it.
I would provide full access to the Analytics page, as well as my server's apache-generated stats (webalizer), and also to all additional information requested.

There are traffic trades involved too (TE3, Xclicks), understanding of these would be necessary.

If you're the man or woman of the situation, you're more than welcome to contact me by PM to talk it out !

(Otherwise, let's be cool persons, if you have recommendations and advice, I'll welcome it already, haha)