Sir,sometimes a person suffering from hyperthyroidism, celiac sprue, allergies to certain food substances, ulcerative colitis,anxiety and most importantly SIBO can also present with the symptoms you have mentioned which is differentiated clinically.so you need to consult a gastroenterologist to ruleout this things. If she has IBS just taking medications is not helpful, following a healthy diet plays a important rule. Avoid spicy foods, junk foods. Avoid coffee and tea. Prefer buttermilk and lassi over that. Eat fresh fruits and vegetables rich in fibres like pears, raspberries, green peas,split peas, lentils, legumes,apples etc are rich in fibres include this things in your diet. Do yoga and meditation to destress since stress can also cause symptoms of IBS.