did you look at your call log and see if an international call was made? if so and you didn't make it, chances are you got the malware that does that. best thing to do is hardreset your phone and install lookout mobile security or something similar.
matter of fact, install it first and see if it finds a virus.
https://www.mylookout.com/
I would go to the website and download the cab directly, so as not to transfer a virus if you have one to your computer, and see what happens.
It runs in the background and I haven't noticed any lag with it running.