Why has my data usage on my Passport suddenly exploded?

Suddenly without any change in my usage I've used up 12 gigs of data on my passport when in the past I've average 2 gigs per cycle. The battery is also draining rapidly. I've checked the browser and it's used up the lions share of this data, but i'm not streaming music or video. I had to buy more data and turned almost every program off and it still spiked. Is this caused by some malware? My carrier wasn't able to help and the phone is out of warranty so i'm stuck without support.

I saw a thread about this awhile ago. Any new knowledge about this?

Are all of your Browser tabs closed?
Clear History. Clear Cookies and Other Data (Settings of the Browser)

This does sound suspicious. YouTube opens in the "browser". Could it be going on and on in the background?

Turn off 'run when minimised' for high battery usage or data usage apps via Device Monitor. Worked for me when I suddenly went from 48 hours to 4 hours batter life!!