why is it that for the last two months, during my period, I have to urinate alot more frequently than normal. I thought I was pregnant at first because I was a few days late. I was two days late again this month and I literally have to urinate every 15-30 minutes. No burning, not infections, no nothing. Just too much. Everything that goes in, comes right back out. (sorry to sound discusting) I have been checked for everything. After my "period" ends, I sort-of go back to normal. Any suggestions?