Help!! Appointment in less than an hour!

This is going to make me sound so dumb probably. I’m only 21 - only been going to the gynecologist since 18 for birth control. I have my annual exam in less than an hour and I just started my period. What do I do? Do I need to call and reschedule? I know normally you can’t with less than 24 hours notice. Can she do the exam if I’m on my period?