Hi Most acne bacteria(Propionibacterium acnes) are anaerobic and will grow rapidly in hair follicles in the absence of oxygen.When they start growing, an inflammatory reaction triggered by your body s defense mechanism(White blood cells) to flush the infection from your skin occurs resulting in the formation of pus-filled bumps.These bacteria make volatile sulfur compounds which are responsible for the smell.A good skin hygiene and some topical antiseptics including anti-septic soaps may help solve the problem.If it persist on these, you can visit a Dermatologist for evaluation. Hope my answer will help you Best regards