How Does Ketoconzole Work In Treatment Of Tinea Vericolour On Chest?

Hi I am suffering from Tinea Vericolour on my chest and back. My doctor prescribed flucos plus lotion but it doesnt seem to be working, have also taken six weeks of 200mg ketoconzole tablets. How is the lotion suppose to work and what do you recommend I use to help clear it up. Many thanks