Why does this keep happening?!

So today im on my third day of my period, and I just started using tampons. Yesterday when I put one in for the first time, I didn't have any problems. But today when I went to school, I had it up there all the way and it was put in correctly, but I had blood come out. I use tampax pearl, I used the regulars, but should I use the supers? My mom said it maybe becuz it's not wide enough, any help.. Thanks :)