Hello there ,
Thanks for writing your query,
Dental pain in an already filled tooth indicates the presence of infection below the filling .
indicates bacterial decay or infection in the tooth that involves the exposed tooth nerve tissues .
such infected tooth needs to be treated by a root canal
procedure so please consider getting the treatment done by consulting a dentist
Formation of lump on the floor of the mouth indicates the abscess
draining in the surrounding area.
you may need an OPG radiographic examination done for your teeth to confirm the spread of infection or to rule out the exact cause of the pain and swelling.
i would suggest you to start with a antibiotic and analgesic
course consulting your dentist , which helps in subsiding the swelling and pain.
i hope this helps ,