Possibly swallowed nails?!

There was a box of nails left on our porch because we were about to hang Christmas lights... Anyways all that's left now is the box that the nails were in and the actual nails are all gone! I looked in the grass and don't see any, but I'm afraid my dog swallowed them?!!! What are the chances? What should I do? We CANNOT afford a vet bill right now! HELLPPP!

*dog seems to be acting fine at the moment, happened about an hour ago?*