Acne vulgaris is physiological, after puberty your sebeous glands which is richly distrubted on face,front & back of the chest is under the influence of androgens, how we responds to that depends on the hereditary. Lack of sleep,frequent travel, stress , menstrual cycle (in female) ..etc may aggravate or flare up the acne.
There are different grades of acne - grade 3 /4 severe form of acne which will end up in the complications like scars & pigmentations.Acne is not one-time treatment it needs to be maintained.
Clinical approach of resistant acne depends on the grade as explained above.
Topical antibiotics & keratolytics..etc.
Systemic antibiotics & Isotretinion(best works in all stages of acne).
Chemical peels like salicylic acid &mandelic acids peels decreases the inflammed acne.
Light therapy & lasers.
Oily skin cleansers.
Next Steps
So please check with near by dermatologist .. upgrade into newer & better treatments once your problem evaluated.