She may be developing Acute Laryngotracheobronchitis (Croup). You should seek expert medical examination and treatment immediately. A doctor can check her chest for air entry, stridor (noisy breathing), chest indrawing, discoloration of skin (cyanosis), mental alertness, fever and local examination such as the throat. The doctor can do an X-ray Neck & Chest to rule out epiglottitis, retropharyngeal abscess or a foreign body in the airway. An infant s airway is narrower and has more lax tissue which swells up faster, causing obstruction. The doctor can get blood tests and culture s done to guide treatment, and maintain humidification, hydration, nebulization and steroids under antibiotic cover.