Any advice on how to soothe a 12 week old baby girl who is teething?

Too young for teeth: A 12 week-old baby is too young for teething. If such a baby is fussy, drooling, not sleeping well, or has mild fever, he may have a throat infection (usually is viral but sometimes is bacterial). A doctor can evaluate and see if medication is needed. A baby at 12 weeks is still under 3 months old, so is pretty young. Parents should not hesitate to contact a doctor for minor symptoms.

Comfort as usual: Kids can have teeth at birth or none till 15mo. I'm not convinced they really have pain with teething though it is an easy sell to parents whose baby is tired& fussy with no abnormality on exam. They mouth fingers a lot because it gives pleasure from touching their lips & suckling. This self soothing activity is quite appropriate & decreases with age.

Chew on cold things : Give her something cold to chew on like a frozen, damp washcloth or cold teething ring. The cold makes the gums feel better, the chewing helps the tooth cut through. Don't give her small things to chew on as they are choking hazards.