As Squad says keep an eye on the situation, you could give NHS direct a call they are normally very good and helpful with advice. A few years ago, I suffered the same kind of pain which I ignored and went into work as per normal. The pain just got worse and worse until I was nearly in tears with it. I started to feel sick and went into the toilet as I was convinced I was going to throw up. I tried to be sick, but instead suddenly the pain disappeared, I think as part of my stomach convulsing. It turned out to be nothing more than wind! I went back into my work department feeling extremely stupid, but luckily my work colleagues were relieved that nothing serious was wrong. So it is possible that wind is what your friend is suffering from, especially if she is getting pains across her back.
I would definately call NHS Direct though for some more advice.
Best wishes to your friend.
Sue