During mini tour for my drum corps (professional marching band. We practice up to 12 hours a day), I got what I thought was my period but it only lasted a day, then it would go away to a white/light brown discharge) then nothing, then a couple days later I would get it again, but only for part of the day, and then it would go away. I'm not really sure what's up with my body, could it be from all the physical activity or what?