I don't think anything.
Depends how bad it is.
And honestly while acne is disgusting it's pretty normal and depending on the severity it's not that bad.
I think you probably think about it more than others do...
If it annoys you so much you should go to a dermatologist and they'll probably...
My phone does the same thing.
It's because there is not enough memory on you phone.
You'll either have to delete something [pictures, etc] or buy an SD card for it [if you phone can use one]