why my toy poodle eats his own "litter"

Help! My 7mths old poodle doesnt eat his food much. i tried feeding him all kind of dog food but he seems to have very little appetite. i even tried introduce him to human food...rice, chicken meat but he seems to show little interest.Instead he would go for his own litter. some people says puppies sometime do that when they are sick but is that true? what should i do to make him eat more proper food and not his own "poo".