Allergic Rhinitis: This is a common condition in toddlers, characterized by an allergic reaction to environmental allergens such as pollen, dust mites, or pet dander, leading to symptoms like rhinitis and throat clearing due to postnasal drip.

Viral Upper Respiratory Infection (URTI): Toddlers are prone to frequent viral infections, which can cause rhinitis and throat clearing. These infections are usually self-limiting but can be recurrent.
Environmental Irritants: Exposure to irritants like tobacco smoke, strong odors, or air pollution can cause rhinitis and throat irritation in toddlers.
Gastroesophageal Reflux Disease (GERD): In toddlers, GERD can manifest with respiratory symptoms, including throat clearing and rhinitis, due to the reflux of stomach contents into the esophagus and potentially into the airways.

Foreign Body Aspiration: Although less common, the possibility of a toddler aspirating a foreign body, which can cause sudden onset of respiratory symptoms including throat clearing, must be considered and ruled out promptly.
Anaphylaxis: A severe, life-threatening allergic reaction that can present with respiratory symptoms among others. Early recognition and treatment are crucial.

Cystic Fibrosis: A genetic disorder that can lead to chronic respiratory infections and inflammation, potentially causing rhinitis and throat clearing among other symptoms.
Primary Ciliary Dyskinesia: A rare genetic disorder affecting the function of cilia, leading to chronic respiratory infections and symptoms like rhinitis.
Tumor or Mass: Although extremely rare in toddlers, a nasal or throat tumor could potentially cause these symptoms and must be considered if other diagnoses are ruled out and symptoms persist.