Hi, thanks for using healthcare magic
It is important to make sure that he receiving the dose that is appropriate for his weight. One common reason for continued pain despite the use of mediation is inadequate amount. The dose is 10 to 15 mg per each Kg in weight per dose.
If he is receiving an adequate amount and still having significant pain then you can consider the use of anti inflammatory pain killers such as ibuprofen
provided he has no reasons he cannot use them.
I hope this helps