Wtf is this?! (Skin problems- picture)

I can't even believe I'm posting this on here, but I'm so desparate for help that I don't even care at this point. Believe it or not this is my butt (I drew out some things lol) and it's covered in whatever this is. I'd like to say it's acne, but it doesn't respond to any acne treatments (believe me, I've spent loads of money on both chemical and natural cures). The only thing it ever really improved a bit with was the (embarrassingly named) "Butt Acne Clearing Lotion" by greenheartlabs. Also, it's not really white heads or black heads, more like just a bunch of red inflammed bumps (as you can see). I have a dermatologist appt soon but I don't even want to show him this, especially because of where it is. I have the same thing going up my back and shoulders. Does anyone have any idea what this is/has ever had it?! I take very good care of my skin so I have no idea why I get this. I thought for a while that I could possibly be hormones so I got a hormone blood test and all reports came back normal.