Do you sort of feel like you have the flu? Two things come to mind as I've also had pain before that feels like I've been kicked in the stomach. On one occasion, it was appendicitis and I had to have emergency surgery to have my appendix removed. On other occasions it was my Crohn's acting up, and a couple times could have even been partial blockage (I have Crohn's of the terminal ileum).
It would probably be a good idea to contact your doctor just to make sure it's nothing serious.
Hope you feel better soon!