when i used minocycline it did pretty much nothing. It is liver toxic so bloodwork should be done when you use it.
Trunkal acne (shoulders, chest, back) is the most difficult to get rid of. I was on 6 months of accutane last year, it sucked ass in a big way, not fun. It did clear me up, but I'm all natural now and have started to get some zits on my shoulders again.
My point? If you use Anabolic Androgenic Steroids (AAS) you'll have acne. Minocycline doesn't help most people. Go to a dermatologist and get on accutane if you really want it gone but realize it will probably come back if you continue aas.