I had candida white tonge dry mouth etc.. now is much better but I have a bad taste sort of bad breath... can nystatin medicine eliminate that prob..

Your best bet would be to find a rinse with chlorine dioxide in it like CloSYS. It can control bad breath for up to 8 hours. I've had many clients who would purchase it over and over again.
CloSYS - dental hygiene advised by Dentists that cures bad breath (http://www.closys.com/)