Why is my iPhone 4 using so much data?

When I first go my iPhone a few months ago, it didn't use much data at all, and I was on it very often. In the past few weeks, it has started using data like crazy. This morning, I reset the data usage in settings (which is how I keep track of it), and I checked it just a few minutes ago. It said I had used 11.9 GB today. I only have a 1 GB plan a month, so you can see how that would be a major issue. I spend 75% of my day in areas where I'm connected to Wi-Fi. My push-notifications have always been disabled. I do not use apps such as Pandora and Spotify to stream music. How could it use that much data in one day?

You have programs running in the background
Double click your home button when your phones unlocked, a row of programs that are running in the background will appear along the bottom, hold one down til they wiggle then you can close them by tapping the little red close circle

For a specific answer for your phone go to the Apple Website then Support and schedule an appointment for the Genius Bar at your local Apple store. It's almost impossible to diagnose your problem in this medium and you need a real solution really fast. 11GB in one day is going to cost you a fortune when your bill arrives.

Soemthing is wrong obviously, call your carrier and talk to them about it, call your apple store… I'm assuming you didn't install something that you are running constantly. Heck I have never used 1 GB in an entire month yet (but I never watch video).