Before you apply the tea tree oil, you have to get rid of the bacteria or possible infection. Apply a solution of 1 part Apple Cider Vinegar (organic, unpasteurized) and 1 part Hydrogen Peroxide in 10 parts water. Leave in for a minute before rinsing out well with water.
A good idea to supplement with the same Apple Cider Vinegar in a dose of two teaspoons in a glass of water once or twice a day.
Tea tree oil is antibacterial and antifungal.