1yr old with rattle/phlem sound in chest, slight cough, no other symptoms.can it be formula, teething or virus?had recent sinus infection.is it serious?

Sinusitis/bronchitis: The sound that your daughter is making may be caused by a number of conditions. These include transmission of sound from the upper airway for example by mucus in the nose. Her recent sinus infection raises the possibility of a recurrence or spread of infection to the lungs. If there is a history of fever recently or respiratory difficulty, she should be checked by her doctor.