Pain during sex🤦🏽‍♀️

I’ve already been having sex with my boyfriend for months now.. But today was the first time I let him take the condom off and it was during missionary I felt sooo much pain. It was like something was weighing very heavily on my stomach and like I had to shit but couldn’t... It was sooo painful.. I never experienced that before. What is this?? I’m scared to ask my mom for help.