What Causes Severe Abdominal Pain And Cramps While Having IBS And GERD?

hi my mom was diagnosed with irritable bowel and GERD in Jan.She wants to know along with the constipation and cramping and bloating she has, why is she getting excrutiating pain in the lower stomach for about an hour as each bout of diarrhea is happening then it stops for ten min and starts all over again until everything is out of her.... could take about an hour. Then she will get the chills, and takes a heating pad to bed, and gets very nauseous and wants to throw up, but doesn t stop her from eating. She wears pessary to keep her bladder up and feels it needs to be changed since she has had it 16 years and everything feels very low, and she gets lots of uti s. She has had bile duct cancer in 2013 and they had to resection the bowel area and also remove the galbladder. They told her no more surgery