How large is the abscess? Is it visible from the outside (enlarged cheek etc.?)
You can try going to ER, but usually in such cases they may refer you back to the dentist. I would suggest calling your dentist and asking for an emergency appointment.
Another thing you mentioned that a day of one antibiotic and a day on another. Were these antibiotics prescribed to you? I find it odd that you were only on either of the medications just one day. It takes days for antibiotics to fight infection, not just one day.
One day antiobiotics are usually prescribed in cases when patients are immunocompromised and prior to appointment (usually about an hour or so) wide range antiobiotics taken, just in case infection may get into the system.
So again, I would refer back to your dentist and stress to him or her that A) You are in pain, B) There is abscess and you want him/her to take care of it.
Hope this helps.
A dentist can't work on an abcessed tooth, they have to get rid of the infection first. They normally do this with antibiotics for 5 to 10 days. I don't quite understand the different antibiotics that you've had here and there. There are emergency dentists in every city, google this in your city and go to one. If this isn't an option, the ER will treat your infection until you can see a dentist...not sure the one you're seeing is the best for you.