Our story is similar to trav's dd was chronically constipated her tummy was full of poo and she would have felt 9 mth pregnant. Only an X-ray could diagnose it. It took over 18 months to resolve with visits to dr's a incontinence nurse a dietician and a psychologist. She was on osmolax first than lactulose which are stool softeners rather than laxatives as they have to get over the fear of going and stop holding on. We also had to change her diet by limiting sugar, no bananas but lots of other fruits, baked beans, oats and nuts were encouraged. If appendix is ruled out ask for an x ray.