Hello and welcome to healthcaremagic
Acne can affect not only the face but the back as well since both these areas are rich in sebaceous glands
Treatment for acne mainly revolves around topical antibacterials (like clindamycin phosphate gel OR Nadifloxacin gel), topical benzoyl peroxide
2.5% gel and topical retinoids.
I would suggest you to use benzoyl peroxide gel for day time application and a topical retinoid for night time application. Both, benzoyl peroxide as well as topical retinoids are effective antiacne medications and would also help to lighten post-inflammatory hyperpigmentation
, benzoyl peroxide being a bleaching agent while retinoids exfoliate the epidermal layers thus shedding off the existing pigment in the processOral antibiotics
like doxycycline or azithromycin can also be greatly useful for inflammatory acne like pustules and papules (as in your case). Therefore a few weeks of oral antibacterials, say 4-6 weeks would bring about faster improvements in your case.
Finally, I would suggest you to undergo a few peeling sessions from a dermatologist
e.g salicylic acid
peel is very useful for active acne whereas glycolic acid peel works really well for post-inflammatory hyperpigmentation.