Hi in my opinion, your immunity has definitely reduced.
You have been having recurrent respiratory tract
If I were your treating doctor I would recommend some investigation which would help us to know the cause of repeated infection and treat you as wise.
I would advise you to get complete blood count
, chest x ray
, sputum for culture and sensitivity.
I would treat you according to the report.
I would also suggest to take some multivitamins and anti oxidants once daily for 3 months to improve your immunity.