I have a couple of thoughts.

1) some reaction to those nerves can come from the needle placement of the anesthetic used. There is an accupunture point right where you describe...a bundle of very sensitive nerves.

2) the swelling from infection may leave lingering swelling you cannot see. This may be pressing on those nerves too.
I had a tooth die...a back molar from being filled wrong, and it caused me terrible grief, until I had a root canal and crown. The swelling was internal and not visible on the face. Much of the infection was going into my sinus on that side. It took just over 6mos before it improved. My dentist put temp cement on that tooth, because of that. He told me that there are nerves between the gum and tooth, proprioceptive nerves that get irritated. There is a procedure to fix this, which I found rather brutal, so I opted for waiting. All settled down finally and I had my permanent seating of the crown.