Period orgasm

When you have an orgasm on your period, what does it do to your flow? For me, immediately after I have an orgasm blood just pours out of me and I start having really bad cramps. If I'm on one of the last days of my period and I'm almost finished, it'll come back again. That's why I don't understand when people say that orgasms are great on your period, mine generally suck and just make me bleed and hurt more.