This is an interesting question. You have a medium/large breed dog, that is good. Now the size of the nail is the next question. The intestines are amazingly forgiving and don't want to be punctured. I once saw a yellow lab who swallowed a sewing needle and we watched it by periodic x-ray as it passed completely through the intestines and out without causing any major problems. I once saw an English Setter who ate a 6 inch metal spike which sat in the stomach and caused the dog significant discomfort. It had to be removed surgically.
I suspect the nail your dog ate was somewhere in between. The good thing about nails is that they are easily seen on an x-ray. You should have one done to find out where it is or if maybe she really never ate it at all. If you see it, the next decision is do you have surgery done to remove it? Although I did watch a dog pass a sewing needle, I would be afraid to leave a nail because if it did puncture, it would set up a potentially serious infection. The other side of the argument- if you leave it and it does pass, you spare your dog a major surgery.
If you had an x-ray done and it was sitting in the stomach, it may be possible to remove it with an endoscope. That would involve anesthesia but no surgery if it could be grabbed by an instrument through the scope. It would have to be very carefully removed so on its way out it does not scratch the inside of the esophagus. An experienced endoscopist could probably do this.
So the decision will need to be made- how to proceed. First, establish that there is a nail in your dog. Then decide the best way to remove it. Your veterinarian will be able to advise you on the best way to handle it. So after all this I will recommend you go see a veterinarian and have the x-ray done.
Hope you find an easily managed situation. Good luck