I need advice!

So, I was running errands and noticed how much pressure was in my pelvic area. It hurt, and I kept having the urge to pee, a lot. (I'm sorry if it's tmi) Since then, I'm assuming it's a UTI because I've had one before and it seemed the same. Except, this time it hurts. It hurts to stand up, and I'm having cramping down there. The pressure is uncomfortable. I can't call my doctors office, because of course... It's Sunday (not open on Sunday's). I don't know what I should do. The pain is tolerable. Should I wait until Monday to call and get a urine test done to confirm, or should I do something sooner? Has this happened to anyone? I'm 21w and 3 days.