Suggest Treatment For The Sunburn On Face

Hi! I have a huge concern on my left side of face. A spot, brown color and when it started, it was by sun exposure and over the years, it became darken. Many doctors said they can't do anything. Currently I am going under a treatment short named as "cold touch", it only resurface to be smoother and less wrinkled, but pigmentation problem still persist. What can I do? I am hyper sensitive skin, fair and easily get acne if I use the wrong product.