Huge drop in sessions - Google Analytics

[pjkcards]

Hello,
I noticed recently that since Aug 5, the number of sessions on the vbulletin forum dropped substantially. I'm trying to figure out why, and I'd appreciate some help.

Here you can see a comparison to the previous 30 days:
https://www.dropbox.com/s/kdynirj6vx...30.21.png?dl=0

Here you can see referral:
https://www.dropbox.com/s/00whdgaf3w...31.47.png?dl=0

So organic, referral, and direct all dropped. No idea why, all in a sudden, on Aug 5 this started. I don't know of any changes made during this time that would have causes this.

Any ideas on what I can do to resolve this issue? Any other vB forums owners notice a change on that date?

Thanks.