Talk to Gastroenterologist on Stool Colour Changed Loose Stools Nausea Vomiting

I am suffering from 2 years of loose stools and nausea vomiting. I did all my blood tests and stool tests are normal even all cultures tests are normal cbc etc everything. Just lil bit high of stool calprotectin level 98.1 which is due to IBS Gastroenterologist told me i m patient of IBS and he told me to do endoscopy but after a week using his medication i dnt feel nausea vomiting even my stool is now solid but sometimes semi solid. My question is my stool colour was yellow solid before 2years but now colour is dark brown.