Can I do anything about this problem with my dog?

He is a Whippet. 2 yeard old. Last year he was bitten by an insect and now he checks his flanks for bites after every two or three steps. Although Whippets are nervy digs, he's not afraid of fireworks, other dogs, loud noises and this newish development is worrying me because it's no fun for him. Can anyone suggest a solution? I brush him and he likes that and I'd hoped it would be enough but it isn't.