Thank you for asking your query.
The itching and irritation could be due to hemorrhoids (piles). This is the most common cause for such symptoms. I assume that you are not having any bleeding from the rectum. You can empirically use OTC ointments like "Smuth" ointment at the anal area (See package insert for instructions). twice a day for 1 week (only. Not more than a week) . Please consult your Doctor regarding this as we cannot offer online prescription.
Eat high fiber diet. Avoid straining in the toilet. High fiber diet will form the cornerstone of therapy.
If the symptoms persist you will have to visit your Doctor for a per rectal examination.
Hope this helps
Please feel free to ask follow up questions.