What Causes White Circular Spots On Skin After Workouts?

Hey, when I workout and sweat after a day or so I notice little circular dots that are lighter then my skin color I went to a dermatologist and he told me it was fungus and prescribed me tersi foam only thing was there were 2 diffrent dots tersi foam only worked on the other dots. I really love to workout sweat and play basketball but if I do I just keep getting spots. Don't know what to do?