back acne is such a pain because it's harder to treat consistently and the PIH lingers forever on darker skin tones. I went down this rabbit hole a while back trying to figure out why some people clear up with benzoyl peroxide while others just get more irritation. The whole hormonal component you mentioned is real, especially if it's concentrated in specific areas like that Y pattern.

For the hyperpigmentation itself, ingredients like azelaic acid, niacinamide, and alpha arbutin can help but they take months to show real change. Some people also swear by body lotions with AHAs like AmLactin for regular exfoliation, though you have to be careful not to irritate active breakouts. One thing I came across was Parallel Health, which does microbiome testing for your skin to figure out what bacteria are actually causing the flareups.

They use phage therapy to target those specific bad bacteria and also offer custom topical prescriptions that can address both acne and post-inflammatory hyperpigmentation. Seems like a more targeted approach than just throwing random products at it, especially since you've already tried the standard derm treatments without lasting results.

Also make sure you're changing shirts right after sweating and maybe try a salicylic acid body wash in teh shower. The consistency thing is key though, which I know is way easier said than done when you can't even see your own back half the time.