Welcome and thanks for posting your query to Healthcare Magic.
As per your query you injured your anal skin. You have not mentioned the exact time period since the injury
is present. Even then generally healing of skin generally takes 7-14 days. Anal skin being prone to infection may take bit longer also. But the exact situation can be told according to level of injury. If it is deep enough then it may take bit longer also. If there is any pus discharge or related thing then you need to meet a surgeon. If there is not then no need to worry you can do "Sitz bath" in which you take warm water in a tub half filled with water. Sit in it for 5 minutes for 3-4 times a day. It will help in healing faster.
Hope these information will help.
"With good health wishes"
Dr Sanjay Kumar Kanodia
MD (Dermatology & STDs)