What is the best way to stop coughing-induced kidney pain?

Tell him to use Otrivin, Nasal spray , 1 squirt into each nostril 3-4 times daily, it is good for coughs and colds. Also Paracetamol tablet 3 times in a day. Hot drinks like tea, soups etc will also help. Try this for 3-4 days, if it is not helpfiul then see a doctor.