In the previous flushes you've been getting floaters. These have made room for other stones which reside in the base of the gallbladder to become free. These acute pains are usually caused by the transit of a stone or sludge moving down the common bile duct. Because the pain passed over in 30 minutes it has probably come out. You may yet see it.......
When the gallbladder neck is blocked the pain is more chronic and cramp like. This is also true for liver pain. So what you explain so vividly is definitely the pain cause by an stone exiting.
I've had this pain myself and it certainly is excruciating but the only thing one can do is try a relax as much as possible. You did well, very very well.
Now you should be almost certain that you have Gallstones or biliary sludge.