Neeedless to say you should have gone directly to the emergency room.
That being said, people have swallowed coins and they have remained inside for many years. You are going to require an x-ray to determine where and if) it is still there. One problem with the coin remaining there is that you can never have an MRI. When you have the x-ray, just be sure to request a shield, which you should double over to cover your ovaries.
If it has not passed they will likely prescribe a concoction to help it do so. The other options depend upon where it is lodged.
There is nothing terribly poisonous about a penny, but you do need an evaluation.
Chances are it has passed.
Since you're still having some pain, I'd say definitely get it checked out just to make sure it's not lodged somewhere. If it's not, chances are they'll just tell you that it'll pass and to watch your stools for a few days to make sure it does. Then, if it hasn't after a few days, more than likely they will either want to "go after it" or at the very least do xrays or scans to see exactly where it is - again to make sure it hasn't lodged somewhere along on the way out.
I would start with your family physician, however, he/she may refer you to a gastroenterologist or perhaps and ENT (ear, nose and throat) doc.
Best of luck and keep us posted.
There is probably one of two things going on... Either the coin is still lodged or it just scratched on the way down either way you should probably get it looked at if it doesnt stop hurting, because if it scratched you may get an infection because well coins arent that clean...
When I swallowed a two dimes. I was told to wait to see if it passes in a few days. If it does not then you need to have them go after it. I remember the nurse saying that most of the time it just works its way out. The ER was right. It did work it's way out in 2 days.