Worst cramps ever!!

I'm 10 weeks today but yesterday while At work I experienced the worst cramping I've ever had in my life. The pain was so bad it made me cry and could barely walk. It was my lower back and pelvic area. I was really worried and kept going to the bathroom to check for blood but there was never any that came out. Today I woke up and don't feel as if I have any pregnancy symptoms which is very unusual because my boobs are usually super sore and I'm nauseous. Im just really worried and don't have another ultrasound for 2 more weeks. Has anyone experienced this before and what happened??