2006 Chevy Trailblazer

,,,Well you never said what year this engine is, but if you had been listening to the motor should have begun to sound like a can of marbles, as the timing chain has apparently jumped a tooth...this a chevy 350 engine? have a mechanic take the timing cover off and inspect the looseness of the chain and position of the sprockets~ Depends on the level of the destruction to the engine to set a price~....gonna be LESS than a rebuilt engine to fix~

the "hammering" part is a bit disconcerting...I've lost a chevy 400...the connecting rod broke and pierced the oil pan...motor toast...welded the pan back and put it onto another rebuilt~

yes 2006....someday I'll learn how to pay attention.~ like almost eight years old already~

The key clue is the oil gauge fluctuating. You ran low on oil. Engine likely toast.