I was constipated for 3 days and then got a lump like flesh near the anus, red and swollen, very painful when walking. After two days, the pus broke with blood and mucus, and the acne healed without any more fluid but did not collapse. I went to the doctor and the doctor said it was an anal fistula but the ultrasound did not show the fistula. 2 days ago, the acne swelled up and burst pus with blood and mucus. So the doctor told me that acne on the anus is a sign of disease? Do you have an anal abscess or an anal fistula? Thank you doctor.