Sex is leaving me sore??

Okay so I’ve been having sex for years and never really had an issue with getting too sore from it. I’ve been having sex with my boyfriend who happens to be really big for months and months now and I get a little sore once in a while but nothing crazy. Recently within the past maybe two weeks or so I’ve been getting so sore it really hurts to have sex for at least 24 hours. We use lube so it’s not from not being wet enough but I feel like something changed and now it hurts to have sex more than once with him. I have an appt at the end of the month with my doctor for a check up and I was going to ask her then as well but I was wondering if anyone’s experienced this. I think it’s weird because it’s never been an issue until now. We’ve had sex four times a night before and I’ve never had an issue being as sore and uncomfortable as I am now. Someone help a girl out.