Dear friend.
Thanks for sharing your concern.
As per your history given,it appears to be an
abscess developed in the periapical area,as your
x ray shows radiolucency there.
If it is your jaw bone,it will appear as opaque object and not a radiolucent one.
But since there is no pain,it might not be infected too.
In this situation,it is better to wait and watch for a week,if it progresses,with pain and pus ,please revisit your
dentist,else it should recover,if due to
anesthetic injection or any inflammatory lesion.
Hope it helps.
Thanks.
Take care.