I'm sorry this is happening to you.
I also had a dark spot on one of my cheeks which was biopsied. It turned out to be nothing concerning, Thank God! The biopsy left me with a tiny divot where they removed the piece to test. The divot looks about like a chicken pox scar. The worst part was wearing a bandaid on my face while waiting for the stitches to heal.
I researched a lot before the biopsy procedure and came to the conclusion that leaving something like this and just watching it is a recipe for disaster. I saw people who had large pieces of their face removed because they waited too long, one even lost an eye.
Cosmetic surgeons can do great things to mend tissue and skin loss if it comes to that but at this point I think a highly qualified dermatologist is your best first step.
Best of luck. @jolinda