Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it is a bad tendency to prick the pimples as it causes increased inflammation and infection in the area of pimples and can lead to gradual darkening due to excessive accumulation of melanin pigment in that area leading to Post Inflammatory Hyperpigmentation.. It although occurs as a protective phenomena but the dark spots left behind are unaesthetic or unsighty.. Also they are stubborn enough and will not get fade off easily.. Glycolic acid peeling is helpful but a single sitting cannot completely resolve the pigmentation.. You need to keep patience and take treatment for a longer period which will involve topical depigmentation creams as well as chair side techniques which will be done at the dermatologist clinic.. You can start applying safer depigmentation creams containing Kojic acid, glycolic acid, arbutin. Creams containing Vitamin E and C are also effective.. Azelic acid preparations can also be applied.. Wash your face atleast twice a day with salicylic acid and glycolic acid containing facewash.. Exfoliate or scrub your skin twice a week with a gentle scrub.. You can also go for another session of chemical peeling while treatments like Microdermabrasion can also be helpful. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.