Can anyone tell me what just happened?

Brittany
I don't know what it was but I am FREAKING out!
I was standing, leaned against a wall and all of a sudden, I felt like I got kicked in the middle of my back, right under my belly button, and on my right butt cheek all at the exact same time. If I wasn't leaned against the wall, I would have fallen. I don't know which direction, but I would have fallen. And yes, it HURT. 
Anyways, now I'm getting a lot of muscle spasms in my pelvis. 
What could possibly be going on?! I'm 37&6, and when I got checked 3 days ago I was high, hard and closed.