Bleeding 2 weeks after period.

I'm a bit worried. My period is very regular. My last one was from January 31 to February 6. No yesterday I started experiencing cramps and u have bleeding but only when I go to the bathroom. What's happening?! 
I will note that I'm currently treating(with antifungal oral medication) a yeast infection that I got from taking antibiotics. 
I'm just wondering if anyone has expect this and if it's serious.