Thank you for visiting EmpowHER and sharing your question about your period.
It is not that uncommon to have early bleeding that comes one day and stops before the onset of your actual period. It could just be your uterus shedding what was left over from the last period.
It's nothing to be alarmed about. However, just for reference, things such as extreme weight changes (increase or decrease) hormonal imbalances including thyroid issues, and pregnancy are conditions that can cause this. If you don't get your next period as scheduled then you can consult your doctor.
Anon, did this help?