@luke05485: Please can you try restarting your phone in Safe Mode, as this will disable all third party apps, and help to determine if the problem is stemming from an external source. To enter Safe Mode, press and hold the Power button until the 'Power off' prompt appears on the screen then release > Touch and hold Power off until the 'Safe mode' prompt appears then release > To confirm, tap Safe mode.
Monitor the device for a few hours, depending on the frequency of the issue. If you notice an improvement then please restart the phone as you would normally, and uninstall any recently added applications.
