Short gut syndrome and low electrolytes

I have 2ft of my small intestines left and I have all of my large intestines.
I have symptoms of dehydration and electrolyte imbalance. Some of my kidney blood results are abnormal because of it according to my kidney doctor. My GI doctor doesn't think it's from dehydration and electrolyte imbalance so he wants to continue to treat my Short gut syndrome symptoms as IBS, my symptoms are not related to IBS. What is a good way to tell my GI doctor that it's not helping me by treating me for IBS?