Migraine: This is often characterized by unilateral headaches, which can be accompanied by facial pain. The fact that symptoms worsen in the morning could be related to various migraine triggers, including sleep patterns and morning stress.

Tension-Type Headache: These headaches are often bilateral but can be unilateral and are typically described as a dull, pressing sensation. They can also involve facial pain and may worsen in the morning due to increased muscle tension during sleep.
Temporomandibular Joint (TMJ) Disorder: TMJ disorders can cause facial pain, particularly in the jaw area, and can radiate to the side of the head, mimicking a headache. Morning worsening could be due to nocturnal bruxism (teeth grinding).
Sinusitis: Although typically associated with more nasal symptoms, sinusitis can cause facial pain and headache, especially if the sinuses on one side are more affected. Morning worsening could be due to increased mucous production overnight.

Giant Cell Arteritis (GCA): Although less common, GCA is a critical diagnosis to consider in patients over 50 with new-onset headache, as it can lead to blindness if not promptly treated. Facial pain can be a symptom, and while it's more commonly associated with jaw claudication and visual symptoms, it should not be missed.
Trigeminal Neuralgia: Characterized by sudden, severe, shock-like pain around the eyes, lips, or nose mainly on one side of the face, it's less likely given the description of dull pain but could be considered if the pain is intermittent and severe.
Cranial Arteritis or Other Vasculitis: These conditions can cause headache and facial pain and are important to diagnose early to prevent complications.

Raeder's Syndrome: A rare condition characterized by a combination of facial pain, typically in the distribution of the trigeminal nerve, and sympathetic dysfunction (e.g., ptosis, miosis). It's a diagnosis of exclusion.
Eagle Syndrome: Caused by an elongated styloid process or calcified stylohyoid ligament, leading to facial and head pain, often unilateral. It's a rare condition that might be considered if other diagnoses are ruled out.
Occipital Neuralgia: Involves the nerves that run from the base of the skull to the scalp and can cause pain on one side of the head, which might radiate to the face. It's less common but could be a consideration in the differential diagnosis.