If you have had a continuous cough with a normal chest X-ray, the common reasons can be allergies (allergic rhinitis), post-nasal drip from sinus issues, mild asthma, or throat irritation, so it is important to consult a doctor for proper evaluation if the cough persists.

If you are sneezing more at night with a dry cough but your chest feels clear, it may be due to allergy or mild airway irritation; you can take Cetirizine or Levocetirizine at night to reduce sneezing, and for dry cough you can use a cough suppressant like Dextromethorphan syrup, along with steam inhalation and warm fluids before bed, and if symptoms persist more than a few days or worsen, consult a doctor for proper evaluation.

Make sure he rests, drinks plenty of water, and utilizes a humidifier or warm liquids to relieve the symptoms of a mild dry cough and cold. If necessary, over-the-counter treatments like saline nasal drops or cough syrup can be helpful. If your symptoms get worse, you get a fever, or you have trouble breathing, you should see a doctor.