Thanks for posting your query.
The halitosis is due to factors like-
poor oral hygiene
maintenance resulting in plaque deposition leading to gingivitis.
immunologically compromised individuals.
systemic conditions like diabetes mellitus
I would suggest you to get a deep scaling and root planning done.
BRush your teeth twice daily using soft-bristled tooth brush.
Clean your tongue to prevent bacterial accumulation.
Check for throat infection.
get your blood sugar level monitored.
mouthrinses can be used to gargle.