I have post-inflammatory hyperpigmentation on my body that is brown in color. I had done TCA peels on cut scars which left me with dark skin where I had applied the peels. I have been using 4% hydroquinone (in a tube from the pharmacy) on these spots once daily for around 25 days now with no change. Am I doing something wrong? The directions on the package do not say to exfoliate beforehand, etc. Would be thankful for any advice.