Tea Tree Oil is good. Also, I don't know if you moisturise after a bath or shower but I stopped moisturising my back and just gave it a good old scrub with a towel. Hope this helps.
I had the same problem. Find out the cause of it. Mine was caused by hot sauna's and steam's then not taking a cold shower afterwards. Problem was the pore's were still open, thus the spots formed. Take a cold shower afterwards. It worked for me.