hello and welcome to HCM forum,
as stated by you, foul odour from mouth, is associated with a number of factors,smoking is one of them, more than that, poor oral hygiene
results in accumulation of calculus which initiates inflammation of gums(gingivitis
) ,followed by periodontitis
according to the history provided by you it seems to be a case of periodontitis which is responsible for foul smell,until diagnosed clinically by a dentist
i would recommend, stop smoking,
get professional cleaning of teeth every 6 months,
use antibacterial mouthwash twice daily,
and brush your teeth twice daily.
i wish you good health.