Respected  user , hi 
Thanks for using Healthcaremagic.com
I have evaluated your query thoroughly .
* Seems most likely 
anal fissure with 
constipation .
* Require multi modality management as
-  High fiber diet with plenty liquids to get soft smooth evacuations .
-  Avoid oily , spicy , non veg .
-  Sitz bath ( sitting in a tub filled with lukewarm water 10 minutes 3 times
                    a day ) help a lot
-  
Benadryl tab. for itching part control
-  Creams  containing lignocaine  give  soothing  action 
-  Keep the area clean with antiseptic liquids , dry 
-  Certain cases need bulk forming laxative as isbaghula husk .
-  Avoid 
smoking , alcohol 
Hope this clears your query .
Welcome for further asssitance .
Regards .