hello visit a dentist get it checked.get an xray done.if there is an infection to the same tooth you will have to repeat the root canal procedure.it is better to check it clinically for proper diagnosis.

Was the root canal treated tooth capped? Its recommended to get it capped unless there was very little damage done due to caries and all the walls were intact. Even otherwise, if it was only filled with an appropriate filling material, as long as you are maintaining healthy oral hygiene practices including flossing, there shouldn't be any food lodgement. If he does have it, get it rechecked/refilled or get a cap done if required/recommended.

Please do a crown on the root canal treated tooth,so that the contacts are tight, preventing food impaction between the adjacent teeth.this will reduce inflammation and bleeding gums.

Hello, You need to get a crown done immediately after RCT . Regards Dr Sumanmakam