HELP! Is someone Stealing my Traffic?

My website is 6 years old and for 6 years I get on average 30,000 unique visitors per month and 2 - 3 Million hits per month. Well all of a sudden in May - my stats DROPPED to 1000 unique visitors and 55,000 hits per month!! As you can see this is a HUGE drop! I did not understand why as I'm still at the top of google.

Well today - I noticed in my Admin panel where my customer register - I noticed nearly 100 fake Profile registrations with KEYWORDS in the address section. This started ironically on April 28!!

It just seems like too much of a coincidence. What type of company or person would I hire to investigate this?

Got this fixed? Kindoff experiencing something like this.

I think I was hit BIG by Panda or Penguin or whatever dum a** update Google had done. It whipped out thousands of long tail keywords that I was getting traffic on. Still have not recovered I don't think the fake profiles had anything to do with it.

What type of site was it jharr? Like a dating site or something?

Thanks

No a hair extension website - ecommerce site.

There is no more information in the "keyword users" then the keywords?

no, that was the only thing