Heya! First time posting here, so hopefully this is the right place for my kind of problem  

I'm dealing with some acne, but somehow I only get it around my mouth/chin nowadays (before I also had it on my nose & forehead, but never on my cheeks luckily). 

Anyways, I'm wondering what to do about these marks that I have, more specifically the yellow one. I haven't really seen anyone else with such yellowish pigmentation - is it even from my acne or something else? I have never been to a dermatologist, more than just asked some cashier on what products that may work for me (none really did, but I also stopped drinking soda & limited fast food which did help alot).

Would appreciate some help here, thanks!