Hello moms, I need your advice. My son is coughing again, with phlegm.…

Hello moms, I need your advice. My son is coughing again, with phlegm. Every time he coughs, it's immediately phlegmy and then bronchitis. This year I got smarter and started treating him without antibiotics (naturally, based on tests). He gets better in a week and plus another week of lingering cough. He didn't get sick in summer. So, what bothers me is that it's not just a common cold, but everything quickly turns into bronchitis. I think we should take him to a pulmonologist, do you think there's any point? And who would you recommend?