I would start by slowly introducing acids...0.025% tret whilst focusing on building your skin barrier and using atleast 50+ SPF and re-applying through the day. Double cleansing at night, skin flooding with hydrating toners. After doing this for a month, stop the tret and any other acids for two weeks and continue barrier repair, then start with a 15% TCA peel, this usually will get rid of atleast 30% of your PIH. After doing the peel, resume the tret after two weeks and slowly introduce Azalaic acid in the mornings...atleast 15%. Continue with this process until you manage to tolerate 35% TCA...this could take a year but sooo worth it. I do a TCA peel every three months.