The same exact thing happened to me this weekend. I have IBS-C and I will be very good for a while and then go on a eating binge. I have always been skinny and have put on 20 lbs with this IBS. So I am also scared of gaining more weight. I also take zelnorm and it works wonders for the pain. It aslo helps me go but I have to take stool softeners with it and used to have to take milk of mag. with it. I have been on it since December and the dr. thinks I will be on it another two years before I become normal. I guess it is a long, long process! Good luck!