I have a yeast infection I'm started using miconazole 3 last night. I had a period 14 day's ago but my period has started last night is it the medicin?

Early bleeding? It is not the medicine. If you are not on oral birth control, the end ofyour "period 14 days ago" (assuming the start was 14 days ago) is about the time of ovulation, which can produce some bleeding, especially if two eggs are ovulating. If the bleeding continues, see your healthcare provider, especially if there is a chance that you may be pregnant.