Poor you, sounds nasty.
I am no dentist, I am just guessing. But I would think that unless you can see someone, the best thing to do is
1) leave it alone - no mouth wash etc as it might irritate it (advice now is not to put cream etc on burns)
2) give it a couple of days see if it heals or gets infected - it might just heal on it's own.
3) avoid anything with sugar as it will encourage infection
4) if you have any sign of infection go see someone immediately (the doc will be able to help I would have thought if you have no dentist)
5) NEVER use left over drugs without medical advice, if you take a couple of unprescibed antibiotics and then stop you are breading resistance to antibiotics in any infection that is starting. REALLY BAD IDEA. You should always take the full course of anti-bacterial drugs and if there are any left dispose of them by taking them to the pharmacist. You really don't want to contribute to bacterial resistance (both for your own good and the wider good).
I hope this helps
The Princess of Power - (BTW I have a talking Unicorn)