feeling extra tight ??

I lost my virginity seven months ago and only slept with my boyfriend. We've been having sex continually for 7 months. When I lost my virginity it hurt a lot because I was super tight. All the sudden this week sex is starting to hurt because I'm feeling extra tight and even my boyfriend said I'm feeling tighter. This morning it hurt so bad because of How tight I was. I'm not sure why this happening ?? I just stopped birth control a month ago if that has anything to do with it ??? And even after my boyfriend eats me out and I'm super wet I'm still super tight down there !! I don't know why! Has this happened to anyone else ?