bad diarrhea when period is supposed to start

this app said I was supposed to start yesterday and AF didn't come. I woke up this morning at 3:30 to really really bad cramps. so I went to the restroom and

I had a red spot in my underwear when I pulled them down as well. I sat on the toilet for a good 15 minutes with terrible diarrhea...😧 when I wiped my toilet paper was completely pink with a few small red clumps in it. I'm just wondering if this could be my period coming that's making me need to use the bathroom like this..