Sore during sex

So, lately I've been SUPER sore during sex and extremely sore afterwards. I've never been this sore before. It was also extremely uncomfortable one night. Has anyone else experienced something like this? I let my husband know and we've been trying to figure out why it's been happening. We've both FINALLY decided we were ready to start ttc #2 and this has gotten me so discouraged. We haven't been having sex very often either. It's just been the past few times the last 2 weeks it's been like this.