I have such a question, when you see that the child is healthy. But su…

I have such a question, when you see that the child is healthy. But suddenly he started coughing often, and this is already a sign of coming flu? What do you do besides drinking and rinsing your nose? Hurry up, it's almost summer, but every month they almost start getting sick. And we don't cover them and eat normally. Maybe on teeth, all kinds come out.