Bleeding after 15 days of period, is it ovulation or implementation or period?

Hormones irregular. If your bleeding started with a normal time to start your period, you most likely have problems with your hormone cycles. If not on birth control pills, which can cause this type of menstrual irregularity, you may need to see your physician and get an examination and some tests to determine if this is related to hormones like thyroid; or issues with the ovaries or the uterus.