Another thing to consider, if you find a bad rod bearing, there's a very good chance the oil hole to that bearing is plugged. If it were oiling it probably wouldn't be knocking. And it doesn't take long to ruin a journal on a crank when no oil is there.
If you find a bad bearing, pull the engine and tear it down.
The crank will need repaired and cleaned. And the metal from the rod failure is likely pumped through out the system. So be prepared to clean the block oil passages as well.
