More than likely it is caused by an app u recently installed thats why sometimes in safe mode it doesnt show up..only because it doesnt allow widgets from apps to work
The phone i have recently fixed, there was a flashlight app causing this ( wich is weird because most android phones come with a pre installed flashlight app) that doesnt mean thats the one causing this on your phone, but could be something similar..
If you dont remember the recent apps uintalled that may be causing this u can try going to play store and under the installed apps section.. unistalling every app u dont use
or try going to the setting under the battery usage section and see whats using up your batteries... Also Some app killers list whats running as well so try killing everythong then calling you phone and see what pops bakk up up on the usage list
Either way good luck and sorry for the long story..i will return and see if all was resolved