i have also pain a lot of time. some time i feel that stone stuck in the bile duct. i went for ultrasound but there was not stone. but my gb was thickned by 3 mm. My doctor told that whether you have no stones but if the gall bladder is swollen or thickened it has no capacity to shrink due to thickining of wall it begains to pain again and again.
Now i think this is the main reason thats why we have pain. In any case when we have gall stones, we can have pain due to acidity, pain due to swollen gall bladder, pain due to stones in bile duct, pain due to overeating, pain due to eat fatty food, pain pain pain and pain etc. etc.