Depends on what happened. He must have had a tear, for it to take that long.
If the Tendon is torn and is not reconnecting properly, or potentially worse still, came away from the Bone, as opposed to tearing in the middle, that could require surgical intervention.
If the tear is a muscle related tear, then again surgery might be the only option.
A tendon based problem could be potentially aided with Cortisone, but I think it's gone beyond that.
He may have to resign himself to the possibility that surgery may be the only option. It shouldn't take this long for a Hamsdtriong problem to heal.
Plus some basic exercises and Icing, would probably only go so far if the problem is very severe instead of mild.