"What should I do? What could it be about? I quickly looked on Google, but the results are not always reassuring."

Based on the symptoms described, it is possible that the individual may have a sinus infection or an ear infection. It is recommended to try using a saline solution for nasal hygiene to reduce pressure in the sinuses and prevent drainage into the throat. Drinking plenty of fluids and using throat lozenges may also provide relief. If symptoms persist for more than 7 days without improvement, it is advisable to consult a doctor for further evaluation and treatment.