Hi, welcome to the forum, the important causes needed to be ruled out are
Deviated nasal
septum (DNS) and allergic rhinitis. These conditions can lead to sinus infection, ear infection and headaches.
Other possibilities are laryngeal web, asthma, any structural abnormalities in the nasal passage such as nasal polyps, hypertrophied turbinates etc.
Recurrent infection is sign of low immunity. You need to increase immunity by proper nutritious food, regular exercise, mental fitness etc.