fixed stone in gallbladder neck

Guys, I have two attacks (not pain, just vomit) more than 2 years ago, in between couple months. I did ultrasound at that time, it showed a stone (1.5cm) in the neck. Now 2 years has passed, I did ultrasound again, it's still there, about the same size, still in the neck. My gallbladder is 9cm by 4.5cm, the report says distended. I feel no symptom at all, no pain, no vomit. I eat very healthy these days.
I am not sure if I need to go to surgery... Kind of worried of the stone stuck in the neck. From the ultrasound image it seems that it's a complete block of the opening. But I should feel pain if complete blocks, unless my gallbladder has distended to such a degree that it don't contract anymore?
Any suggestions? Thanks!
Oh, I also tried the stone dissolution drug Ursofalk for 3 months without any effect (from ultrasound)