can a yeast infection cause a missed period
Any stressor, emotional or physical (even a yeast infection) can alter your cycle. The question is, what caused the yeast infection? Hormonal changes, or taking antibiotics can cause a yeast infection and also mess up your cycle. In any case, if your period is early or late while you are also experiencing a yeast infection, I doubt there is any cause for worry.
Yes, yeast and especially Candida can interfere with your menstrual cycle. If a woman has an ongoing yeast/Candida problem that just refuses to go away, she will almost always experience a disruption in her menstrual cycle.