I have a sore under my right breast that has been there for a month. i try putting cortisone on it but it doesn't heal. it also bleeds sometimes.

Intertrigo: You might be suffering from intertrigo (yeast/fungal infection common in warm sweaty skin folds) so solution would be to stay dry eg baby powder or equivalent. Failing that, we would recommend antifungal powder eg nystatin. Still, it's good idea to check w/your Family Doc to make sure it's not something else. And to be sure you don't have diabetes which can delay healing.