i would advice you to have antibiotic and analgesics.
Maintain oral hygeine using mouthwash twice daily.
Since nothing came in xray means that your tooth is fine.
It seem your gums around that tooth is infected forming
abcess which is called periodontal abcess.it occurs
because of food acculumation between gums and tooth and
under the influence of bacterial action pocket forms resultin
in its deepining leading to pus acculumation and then forming
abcess.since its soft tissue
it cannot be detected thru xray
but diagnosed clinically using probe.
For treatment a solution of betadiene and hydrogen perpxide
is injected in that area .cleanind that area with scalers