frequent/painful urination

Ok, so I just started my period yesterday. I was two days late. And I've been cramping but it hasn't been the normal cramping. I mean first I've been peeing I feel like every 10-20 mins since maybe noon today. And then it also kinda hurts to pee. It's not like a burning sensation, but more like intense pressure as I'm finishing peeing. I mean, I've never experienced this before, is it just something that can happen with periods, or is it something more serious? I mean... Am I just paranoid?