Headache, fever, throat pain, and a dry cough are usually due to a viral infection, such as the flu, which often improves with rest and simple care. Drink plenty of warm fluids, do salt water gargles, take steam, and get good rest to help your body recover. You can take basic pain relief to reduce fever and discomfort, and eat light food. If symptoms become severe, last more than a few days, or you have breathing trouble, consult your doctor

A cough lasting 20 days with a suspected chest infection requires a professional medical evaluation rather than self-medication. Since over-the-counter cough syrups have not provided relief, you may need targeted prescription treatments such as antibiotics (if it is a bacterial infection) or inhalers. These can only be safely prescribed after a doctor listens to your lungs with a stethoscope and potentially orders a chest X-ray. Please do not start any new medications without a physical examination. I strongly advise you to visit a doctor or a local clinic immediately for an accurate diagnosis and the correct prescription.