Kindly visit or consult with dentist as without picture it's not possible to diagnose.

Besides deposits in forms of calculus in mouth,  acidity can also cause halitosis. Sometimes medications may cause halitosis or reduced salivary flow in mouth. Get these ruled out.

Halitosis is due to poor oral hygiene Visit a nearby dentist for further treatment Scaling might be required

Halitosis is usually because of poor oral hygiene but there are other reasons also...she need cleaning once..

Halitosis can occur as a result of poor oral hygiene, systemic illnesses and many other factors. High eosinophil count results in throat infections which can promote bad breath. I suggest you to consult a dentist so as to diagnose the probable cause of bad breath and to discuss the required treatment based on the diagnosis.