There is a possibility that something the size of a nickel might not be able to get through the junction between the esophagus (the food pipe) and the stomach. Once it gets into the stomach it then needs to go through the duodenum, which is the very first part of the intestine and which is somewhat narrower than the rest of the intestine. If it gets through that part of the intestine then the rest of the intestine is fairly large and the stone should be able to travel through the rest of the intestine and you would expect to see it in the stool.
Usually you would expect this to happen within about 4 to 5 days so I am somewhat concerned that you have not seen it in the stool. I would recommend that you call your doctor and have your doctor see her in order to determine if there is a need to look for where the stone is. Depending upon what the stone is made of it may or may not be visible on a plain x-ray.