Help Sudden increase in data usage

[13ilgal]

Over the past several years, I have rarely used more than 500 MB of my 2 GB data plan - most of my traffic is on WiFi. However, this month, the use by the OS alone has shot up to 1.48 GB - most of it running in the background (I retrieved this info from Settings > Data Usage). My 3G Watchdog app reports similar numbers. Most of this is in the last few days.

Any idea how to track what is causing this spike?

Running JB 4.1.2 (U. S.) Carrier is Verizon if that makes any difference.

 

[Rukbat]

MyDataManager will show you which apps are using how much data, mobile and wifi separately.

 

[13ilgal]

MyDataManager will show you which apps are using how much data, mobile and wifi separately.

This looks like a pretty slick app - but will it pick apart WHY the OS is pulling down so much data?