Acne vulgaris is physiological, it depends on the harmonal variations & how you responds to it depends on your hereditary .Stress,lack of sleep , menstrual cycles in females...etc.
Acne lesions appears more common on cheeks, jaw, fore-head ,back & chest...where more number of sebaceous glands are present.
Depending on the grade of acne & type of skin..it will leads to post acne scarring +post inflammatory hyerpigmentation(black spots).
Next Steps
So you need to maintain the skin with good face wash like salicylic, topical antibiotics & keratolytics,systemic antibiotics..if grades are higher means you need to go for systemic retinoids..like isotretinointo control.
Health Tips
In acne vulgaris you need to use medicines to maintain & prevent the complications like scars & pigmentation... its not like one course or once treatment ...maintaince required... meet a dermatologist &get treated.