Acute Tonsillitis: This is the most common cause of tonsillar edema in children, often due to viral or bacterial infections. The age and presentation of the child, along with the severity of the edema, make this a highly plausible diagnosis.

Peritonsillar Abscess: A complication of tonsillitis, where an abscess forms beside the tonsils. It's a common cause of severe tonsillar edema and can be life-threatening if not treated promptly.
Mononucleosis (Infectious Mononucleosis): Caused by Epstein-Barr virus, it can lead to significant tonsillar edema, especially in children. Although less common in two-year-olds, it's still a consideration.
Allergic Reaction: An allergic reaction could cause swelling in the throat, including the tonsils. This could be due to food, medications, or other allergens.

Epiglottitis: Although rare, epiglottitis is a life-threatening condition that can cause significant airway obstruction. It's crucial to consider this diagnosis in any child with severe throat swelling.
Retropharyngeal Abscess: An abscess in the tissues in the back of the throat, which can cause severe swelling and potentially life-threatening airway obstruction.
Angioedema: A severe, potentially life-threatening allergic reaction that can cause rapid swelling of the face, lips, tongue, and throat.

Tonsillar Carcinoma: Extremely rare in children, but any persistent or unusual tonsillar swelling warrants consideration of malignancy.
Kawasaki Disease: A rare condition that mainly affects children under the age of 5, characterized by fever, rash, swelling of the hands and feet, and other symptoms, including potentially significant throat swelling.
Diphtheria: A bacterial infection affecting the membranes of the throat and nose. Although rare in areas with high vaccination coverage, it remains a consideration in unvaccinated children or those traveling from areas where diphtheria is common.