Is it bad to use a tampon while getting rid of a yeast infection and using cream?

Not best: If you have a vaginal yeast infection, the walls of the canal may be inflamed and irritated. An absorbent foreign body like a tampon may aggravate it. Additionally, the cream may be less effective because it will absorb into the tampon rather than coat the walls well. Let the infection pass, then may resume the tampons. If you are concerned about cream spillage, a "light day" pad will be fine.