It seems that you have an ailment known as an anal crack. This condition is characterized by cracks in the skin around the anus, which can lead to blood and/or injury in the rectum. This may be from being constipated, having diarrhea, or simply surviving hard stools. To relieve the pain and the healing process, you should see a dietician who will give you foods rich in fiber. Also, a glass of water every day and the use of over-the-counter creams to cover the corroded area can be used to help ease the pain and promote the area to heal. For sure, the area troubles you, however, you are urged to seek help if the techniques have failed and no improvement has been noticed.