I know you have your conclusion, but I wanted to share a funny story.
When my 20 year old daughter was three, she accidentally swallowed a penny. The doctor said it would pass through fine, but she was crying so I had her sleep with me. She would sleep for about 10 minutes, then start crying in her sleep and wake up crying, and kept doing this until I called the doctor again. He said it was stuck in her esophogus and the esophogus kept tightening around it trying to push it down and was causing her pain, so he had me give her some bread to eat to wash it on down, which worked.
The next morning, my then 4-year-old decided she needed to "accidentally" swallow a coin as well, as she wanted the extra attention her sister had been getting! Fortunately for her (or unfortunately - however she looked at it), it went on down and passed through with no problem.