My maltese dog is eating his pooh! What shall I do to help him grow out of the habit?

He is gorgeous, 3months old, and the whole situation makes me really sad because i am not present when he does it so as to intervene one way or another and help him grow out of the habit. Shall I scold him? And how? He doesn't always do it but even the thought of it makes me concerned about both his health as well as ours. I have only had him for two weeks and i really care for him already. Anybody has any idea? pls share it with me!!! Thank u in advance