Total tmi (I'm sorry)

OK so I have been on pelvic rest to prevent preterm labor because keeping my baby in has been a challenge, well now we are over 38 weeks so my doctor gave me the green light to have sex and we cant! Like we were both beyond in the mood but he couldn't even get in? It's like my vagina had absolutely no depth to it. My significant other looked to see if he could notice any visual differences and he said it looked like there was just a wall and then compared my lady parts to a buthole. I'm not the kind of person to cry wolf and usually get annoyed with people who actually ask if they should go to the doctor's over obvious no brained things but I'm mostly just wondering if anyone else has had any issues like this?? At my last appointment I was dilated to 4.5 cm and that's when my doctor said it was OK to have sex but now I'm confused and freaked out and really don't want to call my hospital and explain that my boyfriend couldn't get it in me because my lady parts have totally closed themselves off unless I have to..