Sharp twinges in uterus?

For about a week and a half now I've been getting these EXTREMELY random twinges or twitches or whatever in my uterus. They catch my extremely off guard, they're like really quick sharp pains that lasts like 4 secs and then go away. It's only happened like 4 times. However, it just happened 5 mins ago and this one lasted about 12 secs. Idk how to describe it but it's not like a cramp. It's like a twinge of stabbing sensitivity or something & it takes the breath out of me. It's enough to make me shout aloud. I always do. AF is due today if that matters any, but I've never had this pain leading up to AF before. Pretty sure I'm not pregnant because I havent had sex since September. Although, the last time that I had sex my boyfriend did cum in me but I've had 2 periods since then. So what could this be?