Why is sex so painful?

Hey there! So I’ve always had a tighter vagina, and I’ve had sex before with other guys and never felt pain. The other day, my boyfriend and I had sex, and it was the most painful thing ever. He’s quite big, and it felt like he was almost hitting my cervix. It hurt so bad it almost burned going in. I know lubrication wasn’t the issue, as we did plenty of foreplay and used a lubricated condom. We’ve had sex a couple of times now, but the pain is still unreal. Does anyone have any tips as to making sex less painful? Has anyone else been in this position?