A combination of topical medications and an oral antibiotic would be a good place to start
Thanks for your question and photo. It looks like you are dealing with moderate inflammatory and nodulocystic acne. If you have not tried any prescription medications previously, I would recommend starting with an oral antibiotic such as doxycycline or minocycline and combining it with topical antibiotics (clindamycin or erythromycin) and topical retinoids (tretinoin, adapalene, or tazarotene). It will also be helpful to use a body wash containing benzoyl peroxide or salicylic acid. A regimen like this will often take 6-12 weeks to work, so do not feel discouraged if you don't see results right away.
I hope this answer is helpful! Best of luck.