Unprotected sex just 2 days after period over is very much safe and literally there is no chance of pregnancy
at all. Taking I- pill within 24 hrs gives additional protection (more than 95%) in preventing unwanted pregnancy. Here, you have nothing to worry.
Now you are getting withdrawal bleeding due to effect of the pill. Next period may be earlier or delayed by 1-2 weeks due to hormonal
Take healthy diet, avoid stress
and maintain genital hygiene properly. Practice safe sex