Thanks for posting the query,
Pain and swelling indicates infection of the tooth that had spread to the adjoining tissue leading to formation of periodontal abscess
Pain can be because of re-infection of the tooth , incompletely done treatment , perforation of the canal at the time of canal preparation .
of abscess is must , it can cause nausea
, vomitting , halitosis
, stomach infections.
I suggest you to take an x-ray of the tooth, depending upon which the treatment will be decided. it will be either extraction of the tooth or re-RCT .
Take tab flemiclav 625 TDS , tab flagyl
400 TDS, tab brufen TDS for three days.
Maintain a good oral hygiene , gargle with saline water 3-4 times a day .
mouthwash twice daily.
Antibiotic and analgesic
will give temporary relief.
Unless you go for drainage of abscess and retreatment of tooth you may exparience pain and infection.
Hope this helps out.