If the the extra-long trim cycle exacerbated that old injury, getting the trim really tightly balanced should help enormously. Agree with the vet that he might also benefit from some short-term NSAID therapy to help control any lingering inflammation.
Depending on exactly what the joint issue is, an injection may also benefit.
Moving forward, things to try would be the usual joint supplements: chondroitin, glucosamine, HA, Mov-Ease. If this has become a chronic issue, products containing devil's claw may provide relief. It does take some trial and error to find what works best for each individual as everyone's reactions to the different supplements are different.
You can send the rads to me at: shilohmom @ outlook . com (remove the spaces)
Jan 2005, RI