Thanks for your reply, I did use the default app to check for data usage, it was coming from tethering, however I cannot find a way to set the range to today only.

I also try to use the Data Usage...

A few moment ago I use my phone's USB tethering to connect to my PC like I always do, however it suddenly drained my 2GB worth of data empty in just 30min, I had never had this problem before.

Is...