I think you are doing the right thing. He could have an abcess and if he is not taking an antibiotic he may need one right away. Linking to an article that says:
"Once the pain kicks in, people who have dental abscesses will often describe it as the worst they’ve ever experienced. If you’ve ever had a root canal (see below), you might have had an abscess.
Get help immediately. An abscess will not go away on its own. Worse, the infection can spread as quickly as overnight (in some cases, however, it can take years to spread). An abscess can cause death when the infection spreads to the brain or heart or when swelling cuts off the airway."
Also, validation for going to the ER:
"If you can’t see a dentist immediately: Consider going to an ER if you have severe pain and/or swelling. If you are having trouble breathing, go to an ER right away."
http://bottomlinehealth.com/a-toothache-can-turn-deadly/