Fissure is a cut in the anal lining which leads to pain and burning sensation while passing motions. It is also associated with passage of blood in stools.
Sinus or fistula will present as a swelling near anus which may or may not be painful, and there will be discharge from it
Next Steps
Please visit a general surgeon, get yourself examined. in case it's a sinus/fistula the doctor may recommend further tests like X ray or MRI.
Health Tips
You may likely require surgery.
avoid constipation by consuming plenty of fibre in diet as well as fluids