I wonder if now that the swelling has gone down if they would be able to see it? Maybe it was hidden by the inflammation.
My other thought is that between the popcorn kernel and all the other stuff you tried to swallow to dislodge it that maybe the kernel isn't really there but it still feels like it because it's scratched? That would make it feel as if there is still something there but really isn't. If that's the case, the meds should resolve it soon.
That's what I was thinking. maybe almost like a scab?? Whatever it is OP. I feel for you. Must be so annoying!! Hope it resolves soon!!