This happened to me couple of hours ago, It hurts really really, oh did i mention really? BAD!
Yea i sat on the toilet and had my Boyfriend check this out, he went like half way in thank god.
Just need time, and maybe a hot bath, and if it gets soo bad like dripping blood then go to the doctors, mine was only a little.
I am about 17 almost 18 and it happens, My boyfriend was almost in tears cuz like i was in tears. We are very very close, (he is the one close) and ya know accidents happen, and i bet he felt soo bad, cuz i bet he doesnt want to hurt you.
So don't worry right now, just take it easy and stay off the horse till you got things under control. But i kinda agree that you should wait till like Senior age, like me. Life gets really confusing till your about 18 and then it get REALLY confusing. Plus not all high school relationships lasts. So just be careful.