Why does skin do this?

Throughout the mornings my face looks bright and glowing and healthy and moisturized.

But then afternoons come and my face would turn to discoloration and it will look dark and dull.

Example: My cheeks would be lighter at the higher parts of it. But the lower part of my cheeks would be dark..? It would look unhealthy.

How do I keep it from doing this? How do i keep it glowing throughout the whole day? What causes this?
I’v tried moisturizing and i’m using proactive. I started like a month ago. But this problem has been happening since i could remember. Is it the food? Anything you know will help :J