Hi there. Sorry you are having this pain. It may be due to muscle spams from cramping before your period? Is there a possibility you have a yeast infection brewing? That can cause irritation that makes you feel this pain/pressure. I've read a hormonal change can cause it. Which also would make sense since you say you are getting ready for a period. Odd though that you've never had it before. Or you might have an infection like PID. So, if it intensifies or continues, you'll need to get checked out. Does ibuprofen take the edge off? That's my go to for relief for these kinds of things!
I remember the stabbing pain during pregnancy. youza! I also get it now sometimes during a heavy period. Oh ya, there is definitely sperm in pre ejaculate and women can get pregnant that way. Take a test! Now, I only got that pressure when I was farther along in pregnancy but maybe you get it earlier. but take a test to be sure! come back and tell me the outcome of that!
Well, I don't know exactly what is happening. It may just be an 'off' period that can happen to anyone at one tie or another. However, I feel you still need to take a pregnancy test. Have you done that yet?