Kidney stone questions, and when do you decide to go to the ER

I've been through 3 laser kidney stone surgeries over the last year. Right now there's a stone in there that feels way too big to pass on its own. It's been parked in the kidney, and tonight while I was lying down I got hit with this brutal sharp pain. My guess is it dropped into the ureter or it's pushing its way toward it. My urologist told me to get a CT scan and we'll figure out next steps after that. This stone hurts a whole lot worse than the pile of other kidney stones I've had. So when exactly is it ER time for a kidney stone? I read that some hospitals will keep you admitted until the surgery when it's that bad, and that's the hospital my urologist works at. And what do they actually do for you if it's wedged in or something like that? Handling this one at home is turning into too much. I've passed kidney stones at work before and been totally fine, but this one is either way bigger or way sharper or something, because it just doesn't feel like the other stones and shards I've gotten out. Any advice would be huge! Also, peeing has been a real struggle these last 4 days. Sometimes it takes me minutes just to get it going, then it starts and stops, and half the time it feels like my bladder never fully empties.