What Causes An Urination Expulsion While In Menstruation?

hi, i am on my menstrual cycle now, i had my last period on April 27 and it's weird that i have started on May 10 in a morning, and when i was urinating that morning, suddenly i hear a splash, and i looked, and it seemed like a round but really dark red thing, its really hard to describe it. I sometimes get the feeling that i was pregnant and now i lost it?