Period or is something wrong?

Tmi warning. So for two or three days it has hurt to pee. But it only hurts at the very end. I get to school(Im a high school senior) and use the restroom. Once im done I check to see if I started my period yet because I was supposed to start in a day or two. In the toilet bowl was a red flakey thing. Im not so sure what it was. Help? And as Im posting this I passed another one. Also it smells a bit funky. Last week I had searing pain in my lower abdomen too...