Hi welcome to Health care magic..........
We could help you better if you can describe what you mean when you say breathing problem. You said she has no cough
, no cold
and no noise from chest but still has breathing problem???
1) sudden onset of breathlessness can be due to Asthama , this requires her to under go a PFT , pulmonary function test which can help to diagnose if she has asthama.
2) Aspiration can cause so but not common in thios age group.
3) Panic attack
can cause sudden breathlessness , but there will be other signs like sweating , dizziness