My iPhone 5 keeps restarting itself.

This started happening randomly. I dont remember dropping it ever.

Every single time i would open some app the screen would get all glitchy and the phone would turn off. And its not even a proper turn off, its like the screen goes blank and the phone reboots itself. It reboots itself a couple of times before i can even see the lock screen.

I've restored it on itunes in DFU mode, I tried it both ways restoring it from a back up and using it as a new iPhone. And still the problem remains. I have 6.1.4 on my phone, I never had this problem with 6.1.3. I've also noticed this happening with mainly people having 6.1.4. Is it some kinda glitch? When the problem was fresh it would turn off with immediate use, 5 times a day, only when i used it. Now its like twice aday whenever im using it. While its on though, all apps work properly and hardware changes such as airplane mode etc all work fine.

What i hav been thinking about is downgrading it back to 6.1.3, But im willing try anything now.

Please help!