I had a black head on my breast, almost 1 and 1/2 inch distant from nipple. With sweating, it became larger. After that some itchy feeling we're there. Suddenly it was hurt by my nail and now it became larger and blackish red in colour. No puss is there. Only the outermost layer skin has tenderness. It's paining. I have applied nadoxin cre and took azithromycin. But it's not healing for 7 days. I am 40 years old. Please advice.