Viral Upper Respiratory Tract Infection (URTI): The combination of soreness behind the eye, plugged ear, small headaches, runny nose, and sneezing are classic symptoms of a viral URTI, commonly known as a cold. The symptoms have been present for a short duration, which aligns with the typical onset and progression of a cold.

Allergic Rhinitis: The symptoms of sneezing, runny nose, and headaches could also suggest allergic rhinitis, especially if the patient has a history of allergies. The soreness behind the eye and plugged ear could be secondary to nasal congestion and sinus pressure.
Sinusitis: Given the location of the pain (behind the eye) and the presence of nasal symptoms, acute sinusitis is a plausible diagnosis. The plugged ear could be related to Eustachian tube dysfunction secondary to sinusitis.

Temporal Arteritis: Although less likely given the patient's age and the nature of the symptoms, temporal arteritis (giant cell arteritis) is a critical diagnosis not to miss due to its potential for causing blindness and other serious complications. The soreness behind the eye could be a symptom of this condition.
Orbital Cellulitis: This is an infection of the tissues surrounding the eye, which could cause pain behind the eye. It's a serious condition that requires prompt treatment to prevent complications.
Mastoiditis: Given the symptom of a plugged ear, mastoiditis (an infection of the mastoid bone in the skull) is a condition that, although rare, could have serious consequences if not diagnosed and treated properly.

Multiple Sclerosis: Optic neuritis, which can cause pain behind the eye, is sometimes a presenting symptom of multiple sclerosis. However, the combination of symptoms described would be unusual for this condition.
Tolosa-Hunt Syndrome: This rare condition causes pain behind the eye and could potentially explain some of the patient's symptoms, but it is much less common and typically presents with more severe and localized pain.