Help :(

I'm 21 weeks, I woke up the morning with such pressure on my uterus, it felt like my bladder was so full, so I peed and it didn't help! It feels like my bladder is going to come out! Like I have to poop, but I don't! What is this! It's been like this all day, and it's very very sore, peeing or sneezing seem to cause me so much pain! It's not a UTI, it's a pressure feeling!