So I've noticed that for a year now sex has become very painful with penetration. In some positions like missionary the pain is heightened. And it's painful in my lower stomach that makes me want to cry during sex. This has never happened to me before and I've been having sex for 5+ years. It almost feels like it's hitting a wall. I'm a pretty petite girl so could it be that I have a small vagina and some penises are just too big for me to handle? Or do I have some type of syndrome? I regularly get checked for std's and always come out clean.