iPhone 5 major glitch

Recently, when using the iphone 5 during a call, FaceTime or texting it will close out (or hang up) then quickly flash between home screens and then lock. The Power button is no longer working, along with the volume buttons and the home botton. It's completely useless and is infuriating!!
Anybody else having or heard of this problem? If you have any answers that will help, I'd appreciate it!!