Ouch My Vagina

So my period was last Tuesday to Sunday and me and my boyfriend did not have sex until tonight. Actually I'll rephrase to "tried" to have sex. I have never had this problem before, and me and him have done it many times with no issue, but today I could not even get it in an inch it hurt so bad. I dont think lubrication is an issue, I have always been more waterfallesque than most girls I know, but I have no idea what it could be. During the last few days of my period I was a bit itchy down there, but only on the outside and nowhere near the hole, so i assumed the tampon string and the new scented toilet paper my roommate bought was the probilem and the itchy cleared up a couple days ago so I dont think I have an infection. But the question still remains... WHY DID IT HURT LIKE I WAS BEING TORN APART?? Please help, Im desperate.