hello and welcome to HCM forum,
i would be glad to answer your query, according to the dental history presented by you it seems that even after completion of root canal treatment
on your tooth, infection has still not resolved.
ideally, antibiotic course is given for a week along with analgesics to provide a temporary pain relief, kindly follow the prescription given by your dentist
, as he/she knows better.
I have not seen the x-ray of your tooth ,therefore i will not be able to tell you about the cause for re-treatment, but i will recommend a few points for you to take into consideration, until you see a specialist;
1. avoid taking hot fluids,
2. do not apply apply hot compresses over the swelling,
3. you can apply cold
compresses over the swelling,
) mouth rinses(twice/day),
5. also, warm saline rinses(3-4 times/day).
kindly follow these steps for a week ,along with the medications.
you will be fine within a week,
i hope i answered your query,
i wish you good health,