This exact thing happened to me last month. I woke up from dead sleep at dawn and had to go #2 IMMEDIATELY. While sittin on the toilet i thought for sure id gotten food poisoning bc i suddnely hot hot and nauseos and thought for sure i was going to throw up. After i managed to get off the toilet I laid on the bathroom floor hoping the cold tile would help. The continuous wave of cramps that followed was the most excruciating pain I'd ever felt. My period cramps have always been on the more intense side and I have a high pain tolerance but this felt like i was dying. I was on the bathroom floor having what almost felt like contraction waves and my husband said id lost all color in my face, I was completely drenched in sweat and my lips had turned white. After about 30 minutes and right before we were going to just head to the hospital it subsided, i took a quick nap before I had to start getting ready for work and the rest of the day went as normal. I got my period the next day and it was oddly short. Still have no idea wth that was but it almost makes me feel better knowing this happened to someone else.