please very important,any dental hygenists? can cavities cause bad breath?

[St.Michael]

...i have a big cavity,and no dental insurance,im tryin to save up for a visit.worried i might need a root canal.but my main concern now is can food get down far enuff to cause bad breath? i pick,floss constantly.if i stick a pick in far enuff i hit a nerve and it kills.it that bad? will a filling suffice?i blow in my hand but it duznt smell to me.