Viral Upper Respiratory Infection (URI): This is the most common cause of fever, nasal congestion, and crusty eyes in a 2-year-old female. The symptoms are typical for a viral infection, and the age of the patient makes this diagnosis more likely due to frequent exposure to viral pathogens in daycare or similar settings.

Bacterial Conjunctivitis: The presence of crusty eyes could suggest bacterial conjunctivitis, especially if the discharge is purulent. This condition often accompanies a URI but can also be a standalone infection.
Influenza: Given the symptoms of fever and nasal congestion, influenza should be considered, especially during flu season. The decreased oral intake could be due to the systemic effects of the flu.
Allergic Rhinitis: Although less likely to cause fever, allergic rhinitis could explain the nasal congestion and possibly the crusty eyes if there's an associated allergic conjunctivitis. However, the fever and decreased oral intake might not fully align with this diagnosis.

Bacterial Meningitis: Although rare, bacterial meningitis is a life-threatening condition that can present with fever and decreased oral intake. The presence of neck stiffness or bulging fontanelles would increase suspicion, but these signs can be subtle in young children.
Pneumonia: Fever and decreased oral intake could be signs of pneumonia, especially if there's associated cough or difficulty breathing. Pneumonia can quickly become severe in young children.
Septicemia: Any sign of systemic infection (fever, lethargy, decreased oral intake) in a young child should prompt consideration of septicemia, a potentially life-threatening condition requiring immediate intervention.

Kawasaki Disease: This condition can present with fever, conjunctivitis (which might appear as crusty eyes), and changes in the oral mucosa, among other symptoms. It's a rare but important diagnosis to consider due to its potential for cardiac complications.
Lemierre's Syndrome: Although rare, this condition involves bacterial pharyngitis followed by septic thrombophlebitis of the internal jugular vein. It could present with fever, neck pain, and systemic symptoms, making it a rare but critical diagnosis not to miss.