i need help

so i’m 13 and i just need help on this app, so today i started my period and it was a very heavy flow. i had a volleyball tournament all day so it was very hard for me. i bled through my skins so i had to get new shorts. every time i would get up, it feels like i was peeing blood. and i looked every 5 minutes and huge blood clots were coming out of me. and i don’t know what to do because i don’t have any parents and i live with my grandma so i feel very uncomfortable talking to her about it. please help!