I am not sure, what kind of bad breath i am having, even not sure, i am having or not. i had, due to decay tooth. i removed it. but now when i rub my gums with finger it smells bad. not sure, is it only coming from mouth or also nose. hard to explain?

Accurate judgment of oral odors is difficult. Our smell system and brain tend to filter out odors that others would notice and even find quite strong. Best to ask a trusted friend or family member to help judge whether you have significant bad breath. Good luck.

Most common cause of bad breath is sulfur producing bacteria infected teeth, infected gums, infected tonsils. But there are other reasons such as accumulated food debris on tongue/between teeth/ in gums pockets, Gerd, diabetes, leukemia. In other words first see your Dentist/Hygienist to eliminate potential dental causes. If not completely resolved, then see your Physician for a physical exam.