About a 2 months ago, I was making out with my bf. I had my underwear on and shorts but he came and I was worried that it might have seeped through my underwear. My period was due 3 weeks after this and was 11 days late. Thankfully, I had a normal period with period pains (I drank parsley tea). About 3 weeks after my period, my uterus feels tense/tight but I have not engaged in any sort of sexual activity. I've never been penetrated in any way. What's causing this tenseness?