Girls i have a problem and need a miracle. please help!?

Its that time of the month for me and tomorrow, sunday, I have to go to NY Ballet Academy for cles all day! 6am- 9pm We're not supposed to wear underwear so its just tights and a leotard. But i'm going to have to. and we only have like 2 breaks. I'm hoping it'll magically be gone by then but i only got in thuresday. Any tips or suggestions or stories like mine please answer :I THANKS