What Causes Bleeding From Urethra During Periods?

Since last year, during my periods, i blled from urethra as well. I can feel clotting coming out of it. many times I go to washroom to check if I am right. And every time I was right. Even my pads stain at both ends and clean inbetween. I have to use extra long ones, still there is always a doubt of staining bed. I now scare to go out of my home those days. I am scared of sitting on a chair even. Please help, why it is happening?
Thanks