Major spam trouble with my website that I can't seem to fix or correct

Hello, I am having major spam trouble with my website. I have never seen anything like this before. In one month I have had over 1,000 spammed user accounts created and over 600 spammed buddypress groups accounts created. And to make things more interesting, I have Akismet installed and running, and it has prevented 6,000 spam attempts. I use a captcha from on my registration to prevent spam and I am using all of the spam prevention features from the WP Security and Firewall protection plugin. I am at a loss as to what to do. This is out of control. What do you think happened, and what should I do to fix it and prevent it from happening again? I am opening up my site to access from the WPMU team. Thanks so much.