Hi, Welcome to health care magic, I have read your query and based on your question,my opinion is as follows. Yellowish colored stools which appear seedy could bey due to bile obstruction but you have already done ultrasound and must have ruled out this possibility. Also,your flank pain,stomach or intestinal pain with nausea could be related to your history of irritable bowel syndrome for which you must be taking symptomatic treatment. If you had a single episode of yellow stool then you need not to be worried as it may get resolved on its own. If it repeats, you will require upper GI scopy along with some blood works like serum bilirubin evaluation, particularly conjugated bilirubin and stool examinations. Meanwhile,Take plenty of fluids with oral rehydration salts and continue with your usual diet. Not to worry. Take over the counter pain killers,antacids and anti-emetics medications with all other medications of your IBS. Hope it helps. Regards,