The way I got rid of my bad breath was by quitting smoking especially chewing tobacco and drinking coffee. In addition, I did two things:
1. Chewed a lot of Extra sugarless gum.
2. After brushing, put a dab of toothpaste on my pointing finger and used it to rub the back and side pockets of my throat. It cleans up those areas toothbrushes and pics can't reach. It is uncomfortable and will make you gag, but it is worth it.
If you try this, please let me know how it turns out.