Postnasal Drip (Upper Airway Secretion): This is a common cause of persistent dry cough, especially at night, due to the accumulation of secretions that drip down the back of the throat. The recent onset of ear irritation could be related to Eustachian tube dysfunction, which is often associated with upper respiratory infections or allergies.

Acute Bronchitis: Although the patient has been treated with antibiotics, if the cause is viral, the treatment would not be effective. The persistence of cough and the addition of ear symptoms could suggest a viral upper respiratory infection affecting both the bronchi and the Eustachian tubes.
Allergic Rhinitis: This condition can cause postnasal drip leading to a dry cough, and it can also cause Eustachian tube dysfunction leading to ear fullness or irritation, especially if the allergies are not well managed.
Sinusitis: Given the duration of symptoms and the lack of response to antibiotics, sinusitis could be a consideration, especially if there are other symptoms like facial pain or headache.

Pertussis (Whooping Cough): Although less common in adults, pertussis can cause a persistent cough that worsens at night. It's crucial to consider this diagnosis due to its contagious nature and the need for specific treatment.
Tuberculosis (TB): A persistent cough that does not respond to typical treatments should raise the suspicion of TB, especially in areas with high prevalence or in individuals with risk factors.
Pneumonia: If the patient has a fever, shortness of breath, or other systemic symptoms, pneumonia should be considered, especially since the initial antibiotic treatment did not resolve the symptoms.

Sarcoidosis: This is a systemic disease that can cause cough among other symptoms. It's less likely but should be considered if other diagnoses are ruled out and the patient has other systemic symptoms.
Interstitial Lung Disease: A group of diseases that affect the lung tissue and can cause a persistent dry cough. These are less common and usually present with other symptoms like shortness of breath.

Re-evaluate the patient: A thorough history and physical examination are crucial, including questions about exposure to allergens, recent travel, and contact with individuals with similar symptoms.
Diagnostic Tests: Consider chest X-ray, complete blood count (CBC), erythrocyte sedimentation rate (ESR), and possibly sinus or lung function tests based on the suspected diagnosis.
Allergy Testing: If allergic rhinitis is suspected, consider allergy testing.
Antibiotic Review: If bacterial infection is still suspected, review the choice of antibiotics and consider a broader spectrum or a change based on culture and sensitivity results if available.
Supportive Care: Ensure the patient is using a humidifier, saline nasal sprays, and is well hydrated. Consider over-the-counter medications for allergy symptoms if applicable.
Referral: If the diagnosis is unclear or if the patient does not respond to initial management, consider referral to a specialist such as an allergist, pulmonologist, or an ear, nose, and throat (ENT) specialist.