Hi ! Possibly during the phase of constipation
, the hard stool might have caused an abrasioin (ulcer) in your anal passage resulting in a fissure in ano
, which was sore at a point of time. This possibly healed of its own once the your bowel movements became normal, and the same healed fissure might be giving rise to a sense of itchiness at the site. I would suggest you to do some sitz bath ( sitting on a tub of luke warm water) twice daily, and maintain hygiene of the area. If the problem continues, then you can consult your family physician for a physical examination who may also give you a deworming medication. Wishing you an earlly recovery.