Apply a medicated cream or gel containing resorcinol, salicylic acid or
benzoyl peroxide. This helps is soaking the oil and helps in peeling away the blackheads.If benzoyl peroxide leaves your skin dry, apply an oil-free moisturizer after 10 mins of applying benzoyl peroxide.
For the skin darkening, you can try various skin creams like hydroquinone, azelaic acid, corticosteroids or tretinoin cream.Apply hydroquinone cream on the scars and it should go away in a few days to months.