There are indeed ways to reduce and perhaps alleviate acne on the back, which as my friend Dr Winston has mentioned, light peels tend to help. This can be combined with certain lasers, especially if the real issue is remnant hyperpigmentation from previous acne.
The above, however, usually requires an intense initial treatment period, followed by maintenance treatment once every 1 to 2 months.
Oral isotretinoin (the medication you were prescribed previously) tends to be a more permanent solution, and though it may fail on initial attempts, repeated low dose regiemes can eventually help to permanently alleviate the issue.
The medication, however, can cause dryness and can complicate existing dermatitis that might co-exist with your acne.
I would advise you be seen and assessed proper in clinic to determine your timeline, expectations and current clinical situation before deciding on the path of treatment.
Best regards,
Shane