We do not prescribe drugs online. Kindly take your baby to the hospital for a review and proper management.

Please, clean the tongue and gum with just cottonwool /washcloth (preferably the latter) dipped in water and used to clean the tongue and gum gently not vigorously. There's no need using glycerine or any other substance.

Have you tried to clean your baby's mouth with clean water and clean wash cloth?
Whitish part that refuse to go after cleaning could probably be thrush

A clean wash cloth with warm water will be just fine. Do not do anything else. You should start using age appropriate tooth paste and brush when your child cuts his first tooth

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.

It is not normal to sleep with the mouth opened. He seems to be experiencing enlarged adenoids. Kindly see a Paediatrician or ENT surgeon for further evaluation and management.

Likely to be Oral thrush, please see a doctor for further evaluation and treatment