iphone 4 says its linked to another itunes account

Hello, just did a recovery mode restore and update. Now its saying its linked with another itunes account and its not my itunes account. I've had the phone since it was new so its not a stolen phone or anything like that. And i can prove that.... Call me crazy but i believe someone cloned my phone or it was hacked some sort of way. Any input or thoughts on the subject, and how can i get this phone unlinked from the unknown itunes account?