Insect bites: The description of the spots resembling insect bites and being mildly itchy aligns closely with this diagnosis. The recent history of cold symptoms could be coincidental or related to an allergic reaction, but the primary presentation suggests insect bites.

Allergic contact dermatitis: This could be a reaction to something the patient came into contact with, possibly related to her recent cold symptoms if she used new medications or products.
Eczema (atopic dermatitis): Given the itchy nature of the spots, eczema is a possibility, especially if the patient has a history of atopic diseases.
Viral exanthem: The recent cold symptoms and the appearance of itchy spots could suggest a viral rash, which is common in various viral infections.

Cellulitis: Although less likely given the description of discrete, itchy spots, cellulitis can present with red, itchy areas and must be considered, especially if there's a history of trauma or infection.
Meningococcemia: This is a severe infection that can cause a rash, often accompanied by other systemic symptoms like fever and cold symptoms. It's crucial to consider this, especially if the patient appears systemically unwell.
Lyme disease: If the patient has been outdoors in areas where ticks are common, Lyme disease could be a consideration, especially if the rash is expanding or has a distinctive "bull's-eye" appearance.

Erythema multiforme: A skin condition characterized by target lesions, which could be itchy and might follow a viral infection or other triggers.
Urticaria: Hives can be itchy and could be related to an allergic reaction, possibly to something the patient was exposed to recently.
Pityriasis rosea: A viral rash that starts with a herald patch, followed by a secondary eruption of oval-shaped, itchy patches.