It is not uncommon that someone swallows their crown(s). The crown will not get stuck in your stomach. Naturally, like everything else that is consumed, it comes out! Crowns are not cheap, therefore you might want to retrieve it. I have a video on YouTube that explains exactly what to do should you swallow your crown. Be brave and strong, it is just like "curbing you dog". Take several plastic shopping bags (the kind you may get from the supermarket) and create a double thickness bag.
Slip half of it under the toilet seat so it stays open and out of the water.
Go ahead and proceed carefully with the next step...All the solid material inside you and hopefully your missing crown should now be in the double bag. You survived!
Remove the bag from under the toilet seat, tie it closed and place it upright in the bathroom wastebasket. Feel for the crown through the outside of the bag. Do what you need, to recover the crown from inside the bag. Wash it off with soap water; do not lose it in the drain! Bring it to the dentist to be sterilizedand have it re-cemented. Best of luck.