What Causes A Line Of Black Spots On Cheeks After Cosmetic Surgery?

I am of African origin and had a transplant about 5 years ago. Soon after, I developed a line of black spots under my left eye akin to marks one would get if having cosmetic surgery and accepted that. Two days ago, I noticed some more black spots, again in a curve downwards on my left cheek and a couple sparsely on my right. I am wondering what would be the probable cause and how I could get rid of them