Period help

Rebekah • I sleep a lot.
Hey guys! 
So, on Christmas I'm leaving for Dallas with the marching band I'm in to perform at the Heart of Dallas bowl game for the school I attend. That day also happens to be the day that I'm starting my period and since I'm from Mississippi it'll be a good 12 hour drive in a bus and I usually have really heavy, hurtful periods. 
Any advice on how to make the ride more comfortable?