is colonoscopy necessary before gallbladder removal?

I was transferred to this doctor who thinks he knows it all and every symptom I was naming he told me that wasn't a gallbladder problem so he was trying to tell me where I was hurting at isn't because of my gallbladder It could be various reasons. I had an ultrasound scheduled at the hospital by my original doctor and they detected my gallstones. I be in pain all the time, so the gallbladder specialist recommended a colonoscopy to see how my stool is..I don't wanna waste my time and end up with a high unnecessary medical bill. He talked as if he was the one hurting and he had x ray vision.