Hi, My Son Is 6 Years And 9 Months Old

Hi, my son is 6 years and 9 months old . He has been breathing from mouth and is finding difficult to sleep peacefully in night . He also has tonsills .it always look he is suffering from cold and cough through out the year . He speaks from nose as complained by teachers . He has heavy breathing ! Really worried about him . Any advice to help him sleep well and breathe from nose.