iTunes Accounts using large amounts of data

Hi, I don't understand but for some reason my data usage for my iPhone 4S jumped DRAMATICALLY just in the past few days. I somehow used over 2 GB of data on my 4G cellular network with just a little web browsing and about an hour of music streaming (something I also do, but typically have about 2 GB is one month -- not three days).

Went into my Cellular usage and found that iTunes Accounts had used 5.6 GB over the past two or three months (I hadn't reset it) and wondered what the heck was it doing? I never download apps or update apps unless I'm on WiFI.

So I reset my celluar data and, again,without doing ANYTHING on the App Store in less than 15 minutes, my iTunes Accounts under System Services had used 51.4 MB of data. Over 50 MB in just 15 minutes without even opening the App Store?

What could this be from? Even iCloud functionality shouldn't be using that much and it hadn't updated since yesterday on WiFi.

Any suggestions on what could be going on and how to stop it?There's no way I could have used 2GB in just three days with as little as I use it for webbrowsing, etc., off of WiFi.