How Can Itching In The Rectum For Over 2 Weeks Be Treated In A Child?

Hello doctor My son is 12 years old . He has been complaining of an itchy rectum since the past 2 weeks. Gave him Tab Zentel last sunday. But the itching has not yet stopped. Last night he was writhing n crying since he had a lot of itching. Also complained about bloating . Applied Candid -b cream to the anus and slightly inside. He was fine for some time but the itch started again . He is in std 8 n terminal exams have begun. Really worried . Please advise Worried mom