Hi Dear,
Understanding your concern.
The symptoms you mention in query are pointing towards
dental abscess .There can be many reason for occurrence like :-
Tooth infection that travels from cavity in tooth to the root tip of tooth .
Gum infection which travel down the root tip .
Trauma to tooth .
Clenching of tooth .
I would suggest you to :-
Do betadin and warm saline rinses 2-3 times a day .
Maintain proper oral hygiene .
Apply orabase gel for irritation and itching .
Take ibuprofen or
acetaminophen for pain and swelling.
consult dentist for proper examination .
Doctor may order X-ray to find out exact cause or to rule to condition like herpes or canker sore .
Doctor may perform root canal , drain the abscess or prescribe antibiotics .
In sever cases dentist preform procedure like apicoectomy .
Hope your concern has been resolved.
Get Well Soon.
Best Wishes,
Dr. Harry Maheshwari