u should get a hida scan done to test your gallbladder function. yellow poop is usually a sign of either extra bile in your poop or undigested fats.
and your dr saying u have ibs (which is very possible) is what they say when they dont know whats wrong. Its a blanket diagnosis to get u out of the office.
Let me guess, they either prescribed u antibiotics and/or nexium or some other acid reflux drug. Also, they probably said to add fiber to your diet.
The truth is, they have no clue what you should do because ibs is super tricky. you have to figure out your triggers. what i suggest is to keep a food journal of everything you eat and drink, as well as your bowel movements. this may help you identify what is causing the ibs.