Hi, I'm Karen. Mm. I Was Going To Ask You

Hi, I'm Karen. Mm. I was going to ask you something. Its because I have no idea what it is. When I go to the bathroom and pee. After it I clean. But I notice when I clean this black white blood thing comes out. Idk what it is. And idk if its part of period. But the weird thing is is that my pad is clean it just has a bit of black white thing In it. Can u tell me what can it be?