Is my website being Attacked?

Hey everyone, I'm not new to Warrior forum but it's a new account (just starting a new life, lol).

I don't want to sound over-dramatic (and I don't feel so yet) but I want to forestall the (possibly evil) events.
Interestingly, same pattern in visitors behavior appeared on two of my related websites (related topic), so that probably cannot be a coincidence.
Here's the case: I noticed a quick change in my site's visitor stats. Change appeared 3 days ago and continues.

Info from google analytics:

• Increased visits (but not visitors);
• Increased bounce rate by 20%;
• decreased avg. time on site by 50%;
• pages/visit dropped.

Thankfully it didn't hurt sales yet.
- I didn't do any changes on my websites.
Google webmasters doesn't show these backlinks, but I found in hostgator cpanel some strange looking domains (subdomains actually) from russia .ru that are linking to my sites (backlinks are not actually there). Most of them look like ***.mybb.ru, ***.rolebb.ru, ***.2bb.ru. I don't know if they're somehow related because I don't know since when they're there.
Possible explanations in my opinion:

• someone wants to hurt my visitor stats and possibly hurt SE rankings;
• someone is getting ready or already attacking my website somehow (I've got antiflood system installed);

I never encountered such behavior.
What do you think? What kind of sign is this?
What can you suggest?