Sure; I don't know the physiology exactly, but the neck is a major weak point in the human body. Sounds to me like just a bit of an interior bruise - a bit of swelling in the right spot (in this case, I think the esophagus) would be noticed much more than if it happened in, say, an arm. Understand, please - I really don't know anything about the anatomy, I've just been hit there a few times myself, and it feels pretty much like you described. IMO, it's not a problem, it'll go away by itself; the swelling is part of the healing process but there's certainly no harm in having a doctor check, just to be on the safe side.