foreign object in nose

My three year old son stuck a small piece of a rubber toy up his nose last month. It was about 1/5th of an inch in diameter and pretty flat. We couldn't see it at all, but we attempted to remove it at home by getting him to sneeze, blowing in his mouth, etc. Nothing worked so we went to the Dr. They didn't see anything in his nose, sent us home and told us to watch for smelly drainage, fever, etc. About 2-3 days later, he came down with a fever. We took him to the e.r. they looked in his nose again, didn't see anything and told us it was probably just a virus since there was no drainage. Well, here we are a full month later. Still no unusual smells of infection, but my son is still sniffing and it sounds like one side is sort of blocked. is it possible its still in his nasal cavity somewhere? Could it be harmful? Should I take him back in and ask for more extensive testing?