Why do certain webpages load on my Macbook, but others won't?

I have a Macbook Pro (mid-2012) that's running on Mountain Lion (10.8.2). Recently, I have had trouble connecting to certain websites.

• I can connect quickly and easily to Outlook, Google, Tumblr
• Sites such as Facebook, YouTube and Netflix will not load at all
  - This is on any of my browsers, Safari, Chrome and Firefox.
  - On Chrome I get the frowny paper that says "No data received" after about five minutes of loading
• I also cannot connect to apps just as the App Store, however, my Spotify is connected and working just fine (not Unlimited)

My room mates both have Microsoft/Windows computers, and have had absolutely no problem connecting to any and all websites.

I have tried rebooting my computer, uninstalling and reinstalling Chrome/Safari/Firefox, messing with my Firewall and clearing caches and cookies, manually entering my IPv4 address, dis- and re-connecting to my wifi (also forgetting and rediscovering saved networks), restarting my router, and verifying and "fixing" disk permissions and whatnot. I feel like I'm running out of options, because I haven't and won't purchase Applecare, and I don't have the funds ready to just take the computer to Best Buy.

What have I not tried?