Hello,
Welcome to Just Answer and thanks for your question. Your father may have developed an anal fistula which is a new channel from the rectum opening at the skin around the anus. You can read more about it below (about half way down the page, after anal fissure). Treatment depends on whether there is an abscess, an infection, Crphn's disease, etc., and may start with medication. Surgery can also be done to repair the fistula.
http://www.gicare.com/diseases/Anal-fissure.aspx
Nurse Practitioner
Board Certified Nurse Practitioner, MS, RN. Private practice and hospitalist experience.