iPhone 5, camera problem

I 've got Iphone 5 about 1 month , with no problem till one day .. I opened camera to take a picture and noticed a spill on the middle of screen. I thought its somthing on camera lens , cleaned them, but it was still there. Anyone know what is it?? Here is a picture , and i used full zoom on iphone for better understanding .
http://imageshack.us/a/img811/989/96452049.jpg