Dear mom, please use clean wash clothes and clean water, once the first tooth erupt switch to a soft tooth brush and age appropriate tooth paste

Bad breath or "Halitosis" in children can occur due to several reasons like poor oral hygiene, mouth breathing, tooth decay, gum disease, infections in the mouth, bacteria on the tongue, dry mouth, tonsil stones, foreign objects in the nose and some medical conditions. Start with improving her oral hygiene by ensuring you brush her teeth for her twice a day and making sure you brush her tongue as well. Take her to see a dentist to exclude oral infections, decay, gum disease etc. If it's still persistent you may need to see a paediatrician as well to exclude other causes.

Clean the tongue and gum with just cottonwool /washcloth (preferably the latter) dipped in water and used to clean the tongue

Bad breath or "Halitosis" in children can occur due to several reasons like poor oral hygiene, mouth breathing, tooth decay, gum disease, infections in the mouth, bacteria on the tongue, dry mouth, tonsil stones, foreign objects in the nose and some medical conditions. Start with improving her oral hygiene by ensuring you brush her teeth for her twice a day and making sure you brush her tongue as well. Take her to see a dentist to exclude oral infections, decay, gum disease etc. If it's still persistent you may need to see a paediatrician as well to exclude other causes.