If he has an absess this is very serious and warrants a visit to after hours, they can treat it with antibiotics and get him seen urgently by a hospital dentist.
In August this year DD, who was on the waiting list for dental surgery, had an absessed tooth. She had been complaining of pain and had trouble sleeping (she was living on nurofen to get a full nights sleep) and then on the friday night her face swelled up like she had elephantitis. We already had a script for abs and got this filled which helped and then on the monday I rang the hospital dentist and was told off for not having her seen straight away at after hours. By Wednesday we were in hospital having the tooth dealt with.
This was all done through the public hospital so we weren't charged.