I would get him to double check he is taking the right dose of meds - if he's taking them regularly they build up in your system a bit. Paracetamol & ibuprofen can both put a strain on your liver & even upset your liver enzymes, so it may be that he couldn't metabolize the alcohol like he would normally. Also, alcohol & codeine are both depressants so if he's had too much of either it could slow heart rate & breathing. Definitely get it checked out if he starts to feel worse or looks clammy or passes out or doesn't bounce back.

And if his level of pain increases def go back to dentist/surgeon who pulled the tooth, because alcohol in the first 3 days is definitely something that can cause a dry socket. I wouldn't wish that kind of pain on anyone.