contractions?

tmi apology in advance,but anyways i’m 35 weeks pregnant (ftm) and my boyfriend and i had sex very recently and have been having it consistently,about once a day maybe. this most recent time,I got really tight,painful feelings in my belly and back/hip area very frequently during and afterwards,I was peeing and it happened again and the pain was so unbearable I couldn’t even stand up for a few moments. any ideas as to what the cause of this could be? I feel as if i’m not able to distinguish contractions from just regular pregnancy pains that occur and wondering if contractions are what could be causing the pain