Can u please share if this issue was resolved? I'm going through the same trouble.
As is the case in the vast majority of increased data usage, you should check the settings on your apps. If you update an app, whether automatically or manually, whether on cellular or wifi, the update CAN change the settings on the app which may result in increased data consumption.
EVERY time you see your data use increase without any obvious changes in your habits, you should ALWAYS check the settings on your installed apps. They could have been changed without your knowledge with an app update.
This is pointed out again and again whenever anyone reports an increased data reporting from Verizon and quite often ends up being the culprit.