Tinea Pedis (Athlete's Foot): This is the most likely diagnosis given the symptoms of itchy feet and toenail fungus. Tinea pedis is a common fungal infection that affects the feet, causing itching, burning, and cracking of the skin, and can also lead to fungal infections of the toenails.

Onychomycosis: A fungal infection of the toenails, which matches the description of "toenail fungus." It can cause yellowing, thickening, and brittleness of the nails.
Dyshidrotic Eczema: A condition characterized by small, itchy blisters on the feet, which could explain the itchy feet symptom.
Contact Dermatitis: An allergic reaction or irritation causing itchy, red skin, which could be a secondary reaction to a treatment or product used for the toenail fungus.

Cellulitis: A bacterial skin infection that can cause redness, swelling, and pain. While less likely, it's critical to rule out due to its potential severity and need for antibiotic treatment.
Deep Vein Thrombosis (DVT): Although rare in children, DVT can cause pain and swelling in the legs and feet. Given the age of the patient (seven years old), this is less likely but should be considered in the differential due to its serious implications.

Pitted Keratolysis: A bacterial infection of the skin on the feet, causing small pits and itchy skin.
Keratoderma: A group of rare skin conditions that cause thickening of the skin on the feet, which could potentially cause discomfort and itching.
Erythrasma: A bacterial or fungal infection that causes brownish patches on the skin, often in the folds, and can be itchy. It's less common on the feet but could be considered in a differential diagnosis for itchy feet.