The cause of pain in the abdomen depends on the site .If you are having pain in the upper abdomen after eating,then it might be due to Stomach problem like Gastritis/Gastric ulcer.
Please take a PPI like Rabeprazole
.If you are on pain killers,stop them.
Instead of taking Duphalac
taking regularly,you can improve your bowel habits with Diet.
Please take plenty of liquids,eat green leafy vegetables,fresh fruits and high fiber diet.
If you strictly follow this,you will not have constipation
If you are having IBS,please take a good Pre and Probiotic
Wish you good health and speedy recovery