Thanks for asking the query ,
As the root canal treatment is not completed swelling can be because of pspread of periapical infection to the surrounding tissues due to deep infection or excessive instrumentation during the procedure .
Visit to the dentist
and get an x-ray done to evaluater the correct periapical condition of the tooth . It need not to be delayed as it may further spread to spaces causing space infections .
and bloated stomach can be side effect as you are on a high dose of amoxicillin
You can tstop the drug and can also take tab odoxil
500mg thrice for 5 days .
Maintain good oral hygiene .
Use saline water gargles 3-4 times a day .
Use 0.2% of chlorhexidine
mouthwash gargles .
Hope this helps out .