Cramping, Pressure and Urge to Push?!!

I am 18 weeks and 4 days pregnant. My obgyn isn’t open yet and I have no clue what to do. Yes I have left a message. I have been cramping ever since I woke up. They are breath taking. I am now feeling a sense of tight pressure all over my abdomen into my pelvic area. Whenever I get the pressure I feel the need to push to get it to stop. Hopefully this is making sense. I am confused on what to do. It doesn’t feel like round ligament pain.