bleeding after using sex toy

I don't know why this happens. The last time I had sex was a month ago. We used protection and I already have gotten my period. With my bf away, I've just been masturbating. The first time was with my finger and I will admit it was a bit rough. I saw I was bleeding alittle. Then after that day it stopped. I masturbate today with my toy. But it was gentle and slow. Not rough at all. I saw that I was bleeding again and it was alittle more than the last time. Why do I keep bleeding after masturbating when it's not even that hard