ummmm problems, i guess.

my cycle usually has been every month but two days ago i started my period, i was 18 days late with a 50 day cycle completion. i wasnt having a miss carriage because ive never had intercourse and i havent started any new medications. i feel like there’s something very wrong, my cramps are also unbearably horrible, and i literally completely bled through an S tampon within it being in me for like 3 minutes, i can barely move the first two days of my period. i really dont want to go get looked at because im super young and that makes me super uncomfortable, if anyone else is or has experienced this please help me out i dont want to be terrified of my body.