Surgery is more likely to set off IBS than one dose of senna, but senna can up cramping when you take it but I don't know of it causing any permanent increase in GI symptoms, especially from one dose. Now people who binge and purge with very high doses of senna over a period of years may be worse off than those that just binge, but any sort of disordered eating can be hard on the GI tract.Usually pain after meals is more about how you ate rather than what you ate. The colon is more active after every single meal every human eats every day of their life. Large, greasy meals or when you wait for as long as possible to eat will set of more colon activity than small frequent meals.You might try some peppermint tea or a couple of Altoids 30 minutes before a meal and see if that helps. Most of the antispasmodics are constipating, but peppermint doesn't seem to be. If the prescription antispasmodics seem OK also try taking them 30 minutes before a meal rather than trying them only after the pain hits.