LOL woman take Midol when its that time of the month....
Don't worry about it, it get it too but not that much i get it cuz i do sets of 50 crunches and sit ups, and after about 25 leg raises, just rest and do it again, no biggy
I get kinda the same thing when I really work my abs....feels like a brutal (almost deadly) cramp (especially at the end of the set) but for only about a second or two..then it goes away...if I continue it comes back after several more reps...
Always just thought that was how (my) abs responded to intense stress?