Your doctor can think what ever he wants but he has responsibility to care for you in a sensitive manner You also have the right to know about the examination in detail so that you can satisfy that the job has been completed properly.
If there isn't any Gallstones on ultrasound or sludge and the bile duct is not dilated then it is pretty certain that you don't have surgical gallstones. There are a few other condition that also give biliary pain such as spasm in the gallbladder muscular wall and a dysfunction of the muscle that regular bile flow.
Sometimes the gallbladder gets lazy and wont contract properly and therefore doesn't purge gallbladder bile on a regular basis. Consequently the bile tends to thicken and this glutinous bile can replicate the symptoms of a gallbladder attack.
Many Doctors do not have the grounding to deal with anomalies in the digestive system so you are left with the hassle of trying to get a specialist or deal with it yourself.