Don't just shower...scrub. you need to exfoliate the shin and remove the dead skin cells. Acne is oil trapped under the dry dead skin on top.
Buy a long handled back brushand use it all over.
Bath 3x a day
Buy some Oxy wash that is 2% salasitic acid and was with that and rinse then lather up again and leave it on
Oxy also make a Benzoyle Peroxide wash that is 10% use it the same way alternating from one to the other.
Use the wash because it has the same concentrations of product in a bigger bottle than the tiny bottle of stuff they have you put on a single zit
I have helped guys clear up nasty acne in 2-3 days with this method
...I ususally require they let me bathe them